Punk in Finland

District 9:n laulajan reppu wrote: ↑

28 Feb 2020, 09:23

top 4 hevibändit wrote: ↑

28 Feb 2020, 07:56

RANKKANA wrote: ↑

28 Feb 2020, 01:29

Physicists may have accidentally discovered a new state of matter

Humans have been studying electric charge for thousands of years, and the results have shaped modern civilization. Our daily lives depend on electric lighting, smartphones, cars, and computers, in ways that the first individuals to take note of a static shock or a bolt of lightning could never have imagined.

Now, physicists at Northeastern have discovered a new way to manipulate electric charge. And the changes to the future of our technology could be monumental.

"When such phenomena are discovered, imagination is the limit," says Swastik Kar, an associate professor of physics. "It could change the way we can detect and communicate signals. It could change the way we can sense things and the storage of information, and possibilities that we may not have even thought of yet."

The ability to move, manipulate, and store electrons is key to the vast majority of modern technology, whether we're trying to harvest energy from the sun or play Plants vs. Zombies on our phone. In a paper published in Nanoscale, the researchers described a way to make electrons do something entirely new: Distribute themselves evenly into a stationary, crystalline pattern.

"I'm tempted to say it's almost like a new phase of matter," Kar says. "Because it's just purely electronic."

The phenomenon appeared while the researchers were running experiments with crystalline materials that are only a few atoms thick, known as 2-D materials. These materials are made up of a repeating pattern of atoms, like an endless checkerboard, and are so thin that the electrons in them can only move in two dimensions.

Stacking these ultra-thin materials can create unusual effects as the layers interact at a quantum level.

Kar and his colleagues were examining two such 2-D materials, bismuth selenide and a transition metal dichalcogenide, layered on top of each other like sheets of paper. That's when things started to get weird.

Electrons should repel one another—they're negatively charged, and move away from other negatively charged things. But that's not what the electrons in these layers were doing. They were forming a stationary pattern.

"At certain angles, these materials seem to form a way to share their electrons that ends up forming this geometrically periodic third lattice," Kar says. "A perfectly repeatable array of pure electronic puddles that resides between the two layers."

At first, Kar assumed the result was a mistake. The crystalline structures of 2-D materials are too small to observe directly, so physicists use special microscopes that fire beams of electrons instead of light. As the electrons pass through the material, they interfere with each other and create a pattern. The specific pattern (and a bunch of math) can be used to recreate the shape of the 2-D material.

When the resulting pattern revealed a third layer that couldn't be coming from either of the other two, Kar thought something had gone wrong in the creation of the material or in the measurement process. Similar phenomena have been observed before, but only at extremely low temperatures. Kar's observations were at room temperature.

"Have you ever walked into a meadow and seen an apple tree with mangoes hanging from it?" Kar asks. "Of course we thought something was wrong. This couldn't be happening."

But after repeated testing and experiments led by doctoral student Zachariah Hennighausen, their results remained the same. There was a new lattice-style pattern of charged spots appearing between the 2-D materials. And that pattern changed with the orientation of the two sandwiching layers.

As Kar and his team had been working on the experimental investigation, Arun Bansil, a university distinguished professor of physics at Northeastern, and doctoral student Chistopher Lane were examining the theoretical possibilities, to understand how this could be happening.

Electrons in a material are always bouncing around, Bansil explains, as they are pulled on by the positively charged nuclei of atoms and repelled by other negatively charged electrons. But in this case, something about the way these charges are laid out is pooling electrons in a specific pattern.

"They produce these regions where there are, if you like, ditches of some kind in the potential landscape, which are enough to force these electrons to create these puddles of charge," Bansil says. "The only reason electrons will form into puddles is because there's a potential hole there."

These ditches, so to speak, are created by a combination of quantum mechanical and physical factors, Bansil says.

When two repeating patterns or grids are offset, they combine to create a new pattern (you can replicate this at home by overlapping the teeth of two flat combs). Each 2-D material has a repeating structure, and the researchers demonstrated that the pattern created when those materials are stacked determines where electrons will end up.

"That is where it becomes quantum mechanically favorable for the puddles to reside," Kar says. "It's almost guiding those electron puddles to remain there and nowhere else. It is fascinating."

While the understanding of this phenomenon is still in its infancy, it has the potential to impact the future of electronics, sensing and detection systems, and information processing.

"The excitement at this point is in being able to potentially demonstrate something that people have never thought could exist at room temperature before," Kar says. "And now, the sky's the limit in terms of how we can harness it."

https://phys.org/news/2020-02-physicist ... state.html

Mitä helvettiä

Tästä tulee ns. Wignerin kide mieleen. Ks. https://en.wikipedia.org/wiki/Wigner_crystal. Oleellisin käsitteellinen ero on siinä, että tossa wanhassa ideassa tarkasteltiin elektronien varauksen järjestäytymistä homogeenisessä positiivisen varauksen taustassa. Tommonen mallisysteemi on aina metalli jos ei ota elektronien vuorovaikutusta huomioon ja kun se tehdään aivan hirveän kalkyylin jälkeen, havaitaankin että hylkivä vuorovaikutus voi myös estää hiukkasia liikkumasta, vaikka kaikki hitut haluaakin päästä kauemmaksi toisistaan Tässä taas on nähty samankaltainen ilmiö oikeassa materiaalisysteemissä.

Toi juttu on kirjoitettu taas siihen tapaan että wow amazing I'm so fucking blown away, mutta niille on kyllä tullu aivan varmasti heti mieleen että jaa no siellä varmaan hilapotentiaali ja elektroni-elektroni -vuorovaikutus pelaa vastakkain. Ihan siisti homma kyllä se että noiden 2d kerrosten orientaatio vaikuttaa systeemin ominaisuuksiin, mutta kysymyksen voisi kääntää niinkin päin että miksi helvetissä ei vaikuttaisi.

Swastik Kar

tauti wrote: ↑

29 Feb 2020, 16:35

Swastik Kar

District 9:n laulajan reppu wrote: ↑

28 Feb 2020, 09:23

top 4 hevibändit wrote: ↑

28 Feb 2020, 07:56

RANKKANA wrote: ↑

28 Feb 2020, 01:29

Physicists may have accidentally discovered a new state of matter

Spoiler:

Humans have been studying electric charge for thousands of years, and the results have shaped modern civilization. Our daily lives depend on electric lighting, smartphones, cars, and computers, in ways that the first individuals to take note of a static shock or a bolt of lightning could never have imagined.

Now, physicists at Northeastern have discovered a new way to manipulate electric charge. And the changes to the future of our technology could be monumental.

"When such phenomena are discovered, imagination is the limit," says Swastik Kar, an associate professor of physics. "It could change the way we can detect and communicate signals. It could change the way we can sense things and the storage of information, and possibilities that we may not have even thought of yet."

The ability to move, manipulate, and store electrons is key to the vast majority of modern technology, whether we're trying to harvest energy from the sun or play Plants vs. Zombies on our phone. In a paper published in Nanoscale, the researchers described a way to make electrons do something entirely new: Distribute themselves evenly into a stationary, crystalline pattern.

"I'm tempted to say it's almost like a new phase of matter," Kar says. "Because it's just purely electronic."

The phenomenon appeared while the researchers were running experiments with crystalline materials that are only a few atoms thick, known as 2-D materials. These materials are made up of a repeating pattern of atoms, like an endless checkerboard, and are so thin that the electrons in them can only move in two dimensions.

Stacking these ultra-thin materials can create unusual effects as the layers interact at a quantum level.

Kar and his colleagues were examining two such 2-D materials, bismuth selenide and a transition metal dichalcogenide, layered on top of each other like sheets of paper. That's when things started to get weird.

Electrons should repel one another—they're negatively charged, and move away from other negatively charged things. But that's not what the electrons in these layers were doing. They were forming a stationary pattern.

"At certain angles, these materials seem to form a way to share their electrons that ends up forming this geometrically periodic third lattice," Kar says. "A perfectly repeatable array of pure electronic puddles that resides between the two layers."

At first, Kar assumed the result was a mistake. The crystalline structures of 2-D materials are too small to observe directly, so physicists use special microscopes that fire beams of electrons instead of light. As the electrons pass through the material, they interfere with each other and create a pattern. The specific pattern (and a bunch of math) can be used to recreate the shape of the 2-D material.

When the resulting pattern revealed a third layer that couldn't be coming from either of the other two, Kar thought something had gone wrong in the creation of the material or in the measurement process. Similar phenomena have been observed before, but only at extremely low temperatures. Kar's observations were at room temperature.

"Have you ever walked into a meadow and seen an apple tree with mangoes hanging from it?" Kar asks. "Of course we thought something was wrong. This couldn't be happening."

But after repeated testing and experiments led by doctoral student Zachariah Hennighausen, their results remained the same. There was a new lattice-style pattern of charged spots appearing between the 2-D materials. And that pattern changed with the orientation of the two sandwiching layers.

As Kar and his team had been working on the experimental investigation, Arun Bansil, a university distinguished professor of physics at Northeastern, and doctoral student Chistopher Lane were examining the theoretical possibilities, to understand how this could be happening.

Electrons in a material are always bouncing around, Bansil explains, as they are pulled on by the positively charged nuclei of atoms and repelled by other negatively charged electrons. But in this case, something about the way these charges are laid out is pooling electrons in a specific pattern.

"They produce these regions where there are, if you like, ditches of some kind in the potential landscape, which are enough to force these electrons to create these puddles of charge," Bansil says. "The only reason electrons will form into puddles is because there's a potential hole there."

These ditches, so to speak, are created by a combination of quantum mechanical and physical factors, Bansil says.

When two repeating patterns or grids are offset, they combine to create a new pattern (you can replicate this at home by overlapping the teeth of two flat combs). Each 2-D material has a repeating structure, and the researchers demonstrated that the pattern created when those materials are stacked determines where electrons will end up.

"That is where it becomes quantum mechanically favorable for the puddles to reside," Kar says. "It's almost guiding those electron puddles to remain there and nowhere else. It is fascinating."

While the understanding of this phenomenon is still in its infancy, it has the potential to impact the future of electronics, sensing and detection systems, and information processing.

"The excitement at this point is in being able to potentially demonstrate something that people have never thought could exist at room temperature before," Kar says. "And now, the sky's the limit in terms of how we can harness it."

https://phys.org/news/2020-02-physicist ... state.html
[/spoiler]

Mitä helvettiä

Tästä tulee ns. Wignerin kide mieleen. Ks. https://en.wikipedia.org/wiki/Wigner_crystal. Oleellisin käsitteellinen ero on siinä, että tossa wanhassa ideassa tarkasteltiin elektronien varauksen järjestäytymistä homogeenisessä positiivisen varauksen taustassa. Tommonen mallisysteemi on aina metalli jos ei ota elektronien vuorovaikutusta huomioon ja kun se tehdään aivan hirveän kalkyylin jälkeen, havaitaankin että hylkivä vuorovaikutus voi myös estää hiukkasia liikkumasta, vaikka kaikki hitut haluaakin päästä kauemmaksi toisistaan Tässä taas on nähty samankaltainen ilmiö oikeassa materiaalisysteemissä.

Toi juttu on kirjoitettu taas siihen tapaan että wow amazing I'm so fucking blown away, mutta niille on kyllä tullu aivan varmasti heti mieleen että jaa no siellä varmaan hilapotentiaali ja elektroni-elektroni -vuorovaikutus pelaa vastakkain. Ihan siisti homma kyllä se että noiden 2d kerrosten orientaatio vaikuttaa systeemin ominaisuuksiin, mutta kysymyksen voisi kääntää niinkin päin että miksi helvetissä ei vaikuttaisi.

Ilmastonmuutoksen ja sen vaikutusten estämiseksi on viime vuosina esitetty mittavia geoengineering-hankkeita. Nyt hollantilaistutkijat esittävät, miten Länsi-Eurooppa voisi suojautua merenpinnan nousulta rakentamalla padon Pohjanmeren ympärille.
Ilmastonmuutoksen on arvioitu nostavan merenpintaa kymmenillä senteillä vuosisadan loppuun mennessä. Vuonna 2500 merenpinta voi joidenkin arvioiden mukaan olla jopa kymmenen metriä nykyistä korkeammalla, tutkijat kirjoittavat tiedotteessaan.
Alankomaiden kuninkaallisen merentutkimusinstituutin tutkija Sjoerd Groeskampin mukaan Skotlannin ja Norjan sekä Ranskan ja Englannin välille kaavailtujen patojen rakentaminen olisi mahdollista sekä teknisestä että taloudellisesta näkökulmasta.


”POHJANMEREN SYVIN kohta Ranskan ja Englannin välillä on vain noin 100 metriä. Skotlannin ja Norjan välillä merialueen keskisyvyys on 127 metriä, syvimmän kohdan ollessa 321 metriä Norjan rannikolla”, Groeskamp toteaa ja huomauttaa, että kiinteitä alustoja on rakennettu jopa 500 metrin syvyyteen.
Skotlannin rannikolta Norjaan ulottuva pato olisi 475 kilometriä pitkä. Englannin kanaalin suun sulkeva pato olisi noin 160 kilometriä pitkä. Pato suojelisi yli 25 miljoonaa eurooppalaista nousevan merenpinnan vaikutuksilta.
Groeskamp laski ruotsalaisen kollegansa Joakim Kjelssonin kanssa, että patojen rakentaminen maksaisi noin 250–500 miljardia euroa. Tutkijat esittelevät ratkaisuaan Bulletin of the American Meteorological Research -tiedelehdessä.

Padon myötä Pohjanmeri muuttuisi täysin itsenäiseksi merialueeksi. Ajan myötä merialueesta tulisi makean veden alue, tutkijat toteavat.
Täysin vailla ongelmia ei tämäkään ratkaisu olisi. Tutkijat huomauttavat, että padolla olisi merkittäviä vaikutuksia mereneläville ja sen myötä kalastukseen. Padon myötä myös ravinteita kuljettava vuorovesivaikutus lakkaisi Pohjanmerellä.
”LOPULLISISSA LASKELMISSAMME meidän täytyy ottaa huomioon myös kalastuksen vähenemisestä aiheutuva taloudellinen haitta, meriliikenteen kustannusten kasvu ja valtavien makeaa vettä joista padon toiselle puolelle kuljettavien pumppujen kustannus.”
Groeskamp toteaa että pato olisi äärimmäinen ratkaisu äärimmäiseen ongelmaan.
”Vaikka se on toteuttamiskelpoinen ratkaisu, ideamme toimii pääasiassa varoituksena. Se kertoo yläpuolellamme vellovan ongelman valtavuudesta.”
”Padon kustannukset ja vaikutukset olisivat valtavat. Laskelmiemme mukaan toimettomuutemme meren pinnan nousun estämiseksi käy kuitenkin useita kertoja kalliimmaksi… Jos emme tee mitään, tämä äärimmäinen pato voi olla ainoa ratkaisumme.”

ana-conda wrote: ↑

02 Mar 2020, 17:36

Siisti ja siisti..

Ilmastonmuutoksen ja sen vaikutusten estämiseksi on viime vuosina esitetty mittavia geoengineering-hankkeita. Nyt hollantilaistutkijat esittävät, miten Länsi-Eurooppa voisi suojautua merenpinnan nousulta rakentamalla padon Pohjanmeren ympärille.
Ilmastonmuutoksen on arvioitu nostavan merenpintaa kymmenillä senteillä vuosisadan loppuun mennessä. Vuonna 2500 merenpinta voi joidenkin arvioiden mukaan olla jopa kymmenen metriä nykyistä korkeammalla, tutkijat kirjoittavat tiedotteessaan.
Alankomaiden kuninkaallisen merentutkimusinstituutin tutkija Sjoerd Groeskampin mukaan Skotlannin ja Norjan sekä Ranskan ja Englannin välille kaavailtujen patojen rakentaminen olisi mahdollista sekä teknisestä että taloudellisesta näkökulmasta.


”POHJANMEREN SYVIN kohta Ranskan ja Englannin välillä on vain noin 100 metriä. Skotlannin ja Norjan välillä merialueen keskisyvyys on 127 metriä, syvimmän kohdan ollessa 321 metriä Norjan rannikolla”, Groeskamp toteaa ja huomauttaa, että kiinteitä alustoja on rakennettu jopa 500 metrin syvyyteen.
Skotlannin rannikolta Norjaan ulottuva pato olisi 475 kilometriä pitkä. Englannin kanaalin suun sulkeva pato olisi noin 160 kilometriä pitkä. Pato suojelisi yli 25 miljoonaa eurooppalaista nousevan merenpinnan vaikutuksilta.
Groeskamp laski ruotsalaisen kollegansa Joakim Kjelssonin kanssa, että patojen rakentaminen maksaisi noin 250–500 miljardia euroa. Tutkijat esittelevät ratkaisuaan Bulletin of the American Meteorological Research -tiedelehdessä.

Padon myötä Pohjanmeri muuttuisi täysin itsenäiseksi merialueeksi. Ajan myötä merialueesta tulisi makean veden alue, tutkijat toteavat.
Täysin vailla ongelmia ei tämäkään ratkaisu olisi. Tutkijat huomauttavat, että padolla olisi merkittäviä vaikutuksia mereneläville ja sen myötä kalastukseen. Padon myötä myös ravinteita kuljettava vuorovesivaikutus lakkaisi Pohjanmerellä.
”LOPULLISISSA LASKELMISSAMME meidän täytyy ottaa huomioon myös kalastuksen vähenemisestä aiheutuva taloudellinen haitta, meriliikenteen kustannusten kasvu ja valtavien makeaa vettä joista padon toiselle puolelle kuljettavien pumppujen kustannus.”
Groeskamp toteaa että pato olisi äärimmäinen ratkaisu äärimmäiseen ongelmaan.
”Vaikka se on toteuttamiskelpoinen ratkaisu, ideamme toimii pääasiassa varoituksena. Se kertoo yläpuolellamme vellovan ongelman valtavuudesta.”
”Padon kustannukset ja vaikutukset olisivat valtavat. Laskelmiemme mukaan toimettomuutemme meren pinnan nousun estämiseksi käy kuitenkin useita kertoja kalliimmaksi… Jos emme tee mitään, tämä äärimmäinen pato voi olla ainoa ratkaisumme.”

https://tekniikanmaailma.fi/tutkijoiden ... 5a20c1-500

tarmo erkale wrote: ↑

29 Feb 2020, 21:05

District 9:n laulajan reppu wrote: ↑

28 Feb 2020, 09:23

top 4 hevibändit wrote: ↑

28 Feb 2020, 07:56

RANKKANA wrote: ↑

28 Feb 2020, 01:29

Physicists may have accidentally discovered a new state of matter

Spoiler:

Humans have been studying electric charge for thousands of years, and the results have shaped modern civilization. Our daily lives depend on electric lighting, smartphones, cars, and computers, in ways that the first individuals to take note of a static shock or a bolt of lightning could never have imagined.

Now, physicists at Northeastern have discovered a new way to manipulate electric charge. And the changes to the future of our technology could be monumental.

"When such phenomena are discovered, imagination is the limit," says Swastik Kar, an associate professor of physics. "It could change the way we can detect and communicate signals. It could change the way we can sense things and the storage of information, and possibilities that we may not have even thought of yet."

The ability to move, manipulate, and store electrons is key to the vast majority of modern technology, whether we're trying to harvest energy from the sun or play Plants vs. Zombies on our phone. In a paper published in Nanoscale, the researchers described a way to make electrons do something entirely new: Distribute themselves evenly into a stationary, crystalline pattern.

"I'm tempted to say it's almost like a new phase of matter," Kar says. "Because it's just purely electronic."

The phenomenon appeared while the researchers were running experiments with crystalline materials that are only a few atoms thick, known as 2-D materials. These materials are made up of a repeating pattern of atoms, like an endless checkerboard, and are so thin that the electrons in them can only move in two dimensions.

Stacking these ultra-thin materials can create unusual effects as the layers interact at a quantum level.

Kar and his colleagues were examining two such 2-D materials, bismuth selenide and a transition metal dichalcogenide, layered on top of each other like sheets of paper. That's when things started to get weird.

Electrons should repel one another—they're negatively charged, and move away from other negatively charged things. But that's not what the electrons in these layers were doing. They were forming a stationary pattern.

"At certain angles, these materials seem to form a way to share their electrons that ends up forming this geometrically periodic third lattice," Kar says. "A perfectly repeatable array of pure electronic puddles that resides between the two layers."

At first, Kar assumed the result was a mistake. The crystalline structures of 2-D materials are too small to observe directly, so physicists use special microscopes that fire beams of electrons instead of light. As the electrons pass through the material, they interfere with each other and create a pattern. The specific pattern (and a bunch of math) can be used to recreate the shape of the 2-D material.

When the resulting pattern revealed a third layer that couldn't be coming from either of the other two, Kar thought something had gone wrong in the creation of the material or in the measurement process. Similar phenomena have been observed before, but only at extremely low temperatures. Kar's observations were at room temperature.

"Have you ever walked into a meadow and seen an apple tree with mangoes hanging from it?" Kar asks. "Of course we thought something was wrong. This couldn't be happening."

But after repeated testing and experiments led by doctoral student Zachariah Hennighausen, their results remained the same. There was a new lattice-style pattern of charged spots appearing between the 2-D materials. And that pattern changed with the orientation of the two sandwiching layers.

As Kar and his team had been working on the experimental investigation, Arun Bansil, a university distinguished professor of physics at Northeastern, and doctoral student Chistopher Lane were examining the theoretical possibilities, to understand how this could be happening.

Electrons in a material are always bouncing around, Bansil explains, as they are pulled on by the positively charged nuclei of atoms and repelled by other negatively charged electrons. But in this case, something about the way these charges are laid out is pooling electrons in a specific pattern.

"They produce these regions where there are, if you like, ditches of some kind in the potential landscape, which are enough to force these electrons to create these puddles of charge," Bansil says. "The only reason electrons will form into puddles is because there's a potential hole there."

These ditches, so to speak, are created by a combination of quantum mechanical and physical factors, Bansil says.

When two repeating patterns or grids are offset, they combine to create a new pattern (you can replicate this at home by overlapping the teeth of two flat combs). Each 2-D material has a repeating structure, and the researchers demonstrated that the pattern created when those materials are stacked determines where electrons will end up.

"That is where it becomes quantum mechanically favorable for the puddles to reside," Kar says. "It's almost guiding those electron puddles to remain there and nowhere else. It is fascinating."

While the understanding of this phenomenon is still in its infancy, it has the potential to impact the future of electronics, sensing and detection systems, and information processing.

"The excitement at this point is in being able to potentially demonstrate something that people have never thought could exist at room temperature before," Kar says. "And now, the sky's the limit in terms of how we can harness it."

https://phys.org/news/2020-02-physicist ... state.html
[/spoiler]

Mitä helvettiä

Tästä tulee ns. Wignerin kide mieleen. Ks. https://en.wikipedia.org/wiki/Wigner_crystal. Oleellisin käsitteellinen ero on siinä, että tossa wanhassa ideassa tarkasteltiin elektronien varauksen järjestäytymistä homogeenisessä positiivisen varauksen taustassa. Tommonen mallisysteemi on aina metalli jos ei ota elektronien vuorovaikutusta huomioon ja kun se tehdään aivan hirveän kalkyylin jälkeen, havaitaankin että hylkivä vuorovaikutus voi myös estää hiukkasia liikkumasta, vaikka kaikki hitut haluaakin päästä kauemmaksi toisistaan Tässä taas on nähty samankaltainen ilmiö oikeassa materiaalisysteemissä.

Toi juttu on kirjoitettu taas siihen tapaan että wow amazing I'm so fucking blown away, mutta niille on kyllä tullu aivan varmasti heti mieleen että jaa no siellä varmaan hilapotentiaali ja elektroni-elektroni -vuorovaikutus pelaa vastakkain. Ihan siisti homma kyllä se että noiden 2d kerrosten orientaatio vaikuttaa systeemin ominaisuuksiin, mutta kysymyksen voisi kääntää niinkin päin että miksi helvetissä ei vaikuttaisi.

Eikös tämä oo ihan suoraa jatkumoa grafeenin "magic angle"-hommille: https://www.nature.com/articles/nature26160 jne.

BARELY LEGAL PIKKUPUPU LADYBOY wrote: ↑

02 Mar 2020, 17:55

Ai äiti ehtikin ensin.

District 9:n laulajan reppu wrote: ↑

28 Feb 2020, 09:23

top 4 hevibändit wrote: ↑

28 Feb 2020, 07:56

RANKKANA wrote: ↑

28 Feb 2020, 01:29

Physicists may have accidentally discovered a new state of matter

Humans have been studying electric charge for thousands of years, and the results have shaped modern civilization. Our daily lives depend on electric lighting, smartphones, cars, and computers, in ways that the first individuals to take note of a static shock or a bolt of lightning could never have imagined.

Now, physicists at Northeastern have discovered a new way to manipulate electric charge. And the changes to the future of our technology could be monumental.

"When such phenomena are discovered, imagination is the limit," says Swastik Kar, an associate professor of physics. "It could change the way we can detect and communicate signals. It could change the way we can sense things and the storage of information, and possibilities that we may not have even thought of yet."

The ability to move, manipulate, and store electrons is key to the vast majority of modern technology, whether we're trying to harvest energy from the sun or play Plants vs. Zombies on our phone. In a paper published in Nanoscale, the researchers described a way to make electrons do something entirely new: Distribute themselves evenly into a stationary, crystalline pattern.

"I'm tempted to say it's almost like a new phase of matter," Kar says. "Because it's just purely electronic."

The phenomenon appeared while the researchers were running experiments with crystalline materials that are only a few atoms thick, known as 2-D materials. These materials are made up of a repeating pattern of atoms, like an endless checkerboard, and are so thin that the electrons in them can only move in two dimensions.

Stacking these ultra-thin materials can create unusual effects as the layers interact at a quantum level.

Kar and his colleagues were examining two such 2-D materials, bismuth selenide and a transition metal dichalcogenide, layered on top of each other like sheets of paper. That's when things started to get weird.

Electrons should repel one another—they're negatively charged, and move away from other negatively charged things. But that's not what the electrons in these layers were doing. They were forming a stationary pattern.

"At certain angles, these materials seem to form a way to share their electrons that ends up forming this geometrically periodic third lattice," Kar says. "A perfectly repeatable array of pure electronic puddles that resides between the two layers."

At first, Kar assumed the result was a mistake. The crystalline structures of 2-D materials are too small to observe directly, so physicists use special microscopes that fire beams of electrons instead of light. As the electrons pass through the material, they interfere with each other and create a pattern. The specific pattern (and a bunch of math) can be used to recreate the shape of the 2-D material.

When the resulting pattern revealed a third layer that couldn't be coming from either of the other two, Kar thought something had gone wrong in the creation of the material or in the measurement process. Similar phenomena have been observed before, but only at extremely low temperatures. Kar's observations were at room temperature.

"Have you ever walked into a meadow and seen an apple tree with mangoes hanging from it?" Kar asks. "Of course we thought something was wrong. This couldn't be happening."

But after repeated testing and experiments led by doctoral student Zachariah Hennighausen, their results remained the same. There was a new lattice-style pattern of charged spots appearing between the 2-D materials. And that pattern changed with the orientation of the two sandwiching layers.

As Kar and his team had been working on the experimental investigation, Arun Bansil, a university distinguished professor of physics at Northeastern, and doctoral student Chistopher Lane were examining the theoretical possibilities, to understand how this could be happening.

Electrons in a material are always bouncing around, Bansil explains, as they are pulled on by the positively charged nuclei of atoms and repelled by other negatively charged electrons. But in this case, something about the way these charges are laid out is pooling electrons in a specific pattern.

"They produce these regions where there are, if you like, ditches of some kind in the potential landscape, which are enough to force these electrons to create these puddles of charge," Bansil says. "The only reason electrons will form into puddles is because there's a potential hole there."

These ditches, so to speak, are created by a combination of quantum mechanical and physical factors, Bansil says.

When two repeating patterns or grids are offset, they combine to create a new pattern (you can replicate this at home by overlapping the teeth of two flat combs). Each 2-D material has a repeating structure, and the researchers demonstrated that the pattern created when those materials are stacked determines where electrons will end up.

"That is where it becomes quantum mechanically favorable for the puddles to reside," Kar says. "It's almost guiding those electron puddles to remain there and nowhere else. It is fascinating."

While the understanding of this phenomenon is still in its infancy, it has the potential to impact the future of electronics, sensing and detection systems, and information processing.

"The excitement at this point is in being able to potentially demonstrate something that people have never thought could exist at room temperature before," Kar says. "And now, the sky's the limit in terms of how we can harness it."

https://phys.org/news/2020-02-physicist ... state.html

Mitä helvettiä

Tästä tulee ns. Wignerin kide mieleen. Ks. https://en.wikipedia.org/wiki/Wigner_crystal. Oleellisin käsitteellinen ero on siinä, että tossa wanhassa ideassa tarkasteltiin elektronien varauksen järjestäytymistä homogeenisessä positiivisen varauksen taustassa. Tommonen mallisysteemi on aina metalli jos ei ota elektronien vuorovaikutusta huomioon ja kun se tehdään aivan hirveän kalkyylin jälkeen, havaitaankin että hylkivä vuorovaikutus voi myös estää hiukkasia liikkumasta, vaikka kaikki hitut haluaakin päästä kauemmaksi toisistaan Tässä taas on nähty samankaltainen ilmiö oikeassa materiaalisysteemissä.

Toi juttu on kirjoitettu taas siihen tapaan että wow amazing I'm so fucking blown away, mutta niille on kyllä tullu aivan varmasti heti mieleen että jaa no siellä varmaan hilapotentiaali ja elektroni-elektroni -vuorovaikutus pelaa vastakkain. Ihan siisti homma kyllä se että noiden 2d kerrosten orientaatio vaikuttaa systeemin ominaisuuksiin, mutta kysymyksen voisi kääntää niinkin päin että miksi helvetissä ei vaikuttaisi.

Some truths about the Universe and our experience in it seem immutable. The sky is up. Gravity sucks. Nothing can travel faster than light. Multicellular life needs oxygen to live. Except we might need to rethink that last one.

Scientists have just discovered that a jellyfish-like parasite doesn't have a mitochondrial genome - the first multicellular organism known to have this absence. That means it doesn't breathe; in fact, it lives its life completely free of oxygen dependency.