PHYSICS/BK21 SEMINAR[09.08.20]
관련링크
본문
"Two-dimensional semimetaland excitonic insulator
Ø바카라 먹튀Speaker :바카라 먹튀 Dr.바카라 먹튀Z. D. Kvon [Institute of Semiconductor Physics, Novosibirsk, Russia]
Ø바카라 먹튀Place : Physics Seminar Room (Science Bldg, 3-201)
Ø바카라 먹튀Date & Time :바카라 먹튀Aug, 20 (Thu), 15:00 ~ 16:00 pm
Abstract
The talk is devoted to the results of the experimental study of a principally new 2D electron system: a two-dimensional (2D) semimetal,바카라 먹튀recently바카라 먹튀realized for바카라 먹튀the first time in quantum wells (QWs) on basis of zero gap semiconductor HgTe. It is shown that this 2D semimetal exists in바카라 먹튀wide바카라 먹튀(thickness of 18 nm – 21 nm) undoped HgTe QWs with바카라 먹튀the바카라 먹튀reduced바카라 먹튀symmetry바카라 먹튀surfaces (such as (013)바카라 먹튀and (112)).바카라 먹튀Because바카라 먹튀of바카라 먹튀an inverted band structure and respectively the peculiar properties of바카라 먹튀size바카라 먹튀quantization바카라 먹튀in바카라 먹튀these바카라 먹튀QWs바카라 먹튀the overlap of a conductance band (with the bottom in the centre of Brillouin zone) and valence band (with the few maximums in its side points) arises. Its value is about 10 meV. So due to this overlap we have the true 2D semimetal similar to that of classical 3D semimetals such as Bi, Sb or As and there is the opportunity to realize the simultaneous existence of an equilibrium gas or liquid of 2D electrons and 2D holes.바카라 먹튀Moreover by means of the field effect transistor structure fabricated on the basis of QW we are바카라 먹튀able바카라 먹튀by바카라 먹튀means바카라 먹튀of simple changing of바카라 먹튀the바카라 먹튀gate바카라 먹튀voltage,바카라 먹튀firstly,바카라 먹튀to바카라 먹튀realize바카라 먹튀and바카라 먹튀study바카라 먹튀transition바카라 먹튀2D바카라 먹튀electron바카라 먹튀metal – 2D semimetal – 2D hole metal and, secondly,바카라 먹튀2D semimetallic바카라 먹튀state with any ratio between the densities바카라 먹튀of 2D electrons (Ns) and 2D holes (Ps). So a lot of new interesting properties caused by their바카라 먹튀simultaneous existence have been observed. These are: 1) sign-variable Hall effect and positive magnetoresistance; 2) electron바카라 먹튀mobility바카라 먹튀jump바카라 먹튀due바카라 먹튀to바카라 먹튀hole바카라 먹튀screening바카라 먹튀of바카라 먹튀electron바카라 먹튀scattering바카라 먹튀by바카라 먹튀impurities, 3)바카라 먹튀anomalous temperature dependence of 2D semimetal resistance because of electron scattering by heavy holes. It is likely this effect is the first clear demonstration of the바카라 먹튀direct바카라 먹튀influence바카라 먹튀of바카라 먹튀a바카라 먹튀particle-particle바카라 먹튀inelastic Landau scattering on metal resistance and correspondingly of Pauli exclusion바카라 먹튀principal.바카라 먹튀But바카라 먹튀the바카라 먹튀most exiting opportunity appearing due to realization of 2D semimetal is to carry out바카라 먹튀the바카라 먹튀direct바카라 먹튀experimental observation of excitonic insulator (EI) state predicted almost fifty years ago by one바카라 먹튀of바카라 먹튀the바카라 먹튀greatest바카라 먹튀20 century condense matter physicists sir Nevill Mott. In 1961 he considered a semimetal and assumed that the Coulomb interaction between electrons and holes have to lead to the formation of their bound바카라 먹튀state and a semimetal should become an insulator. It is surprising but till now this very interesting and important transition has not been directly observed. The main reason of this situation is that till the last바카라 먹튀time바카라 먹튀there was absent the system in which this transition could be realized and then바카라 먹튀directly바카라 먹튀fixed바카라 먹튀by바카라 먹튀resistance measurement. Conventional tree-dimensional semimetal such as Bi or Sb did바카라 먹튀not바카라 먹튀fit바카라 먹튀because바카라 먹튀of바카라 먹튀the absence of the simple procedure to change the density of electron and holes. So in our 2D semimetal the EI state induced by magnetic field is found. It arises between electron-like and hole-like quantum Hall liquid states at the point Ns = Ps and near it. It바카라 먹튀is바카라 먹튀shown바카라 먹튀that바카라 먹튀the바카라 먹튀transition바카라 먹튀metal – EI바카라 먹튀is바카라 먹튀similar바카라 먹튀to superconductor-normal metal transition and described by BCS (Bardeen-Coopper-Schrieffer)-scenario: up to the critical temperature Tc ≈ 1 K no temperature dependence of the바카라 먹튀transport바카라 먹튀and바카라 먹튀capacitance response of the system is바카라 먹튀observed바카라 먹튀but just바카라 먹튀below바카라 먹튀this바카라 먹튀temperature바카라 먹튀the바카라 먹튀strong바카라 먹튀insulator바카라 먹튀behavior characterizing by the gap of about few Kelvins appears.
Contact Person : Prof. Hu-Jong Lee(054-279-2072,바카라 먹튀hjlee@postech.ac.kr)
"
Ø바카라 먹튀Speaker :바카라 먹튀 Dr.바카라 먹튀Z. D. Kvon [Institute of Semiconductor Physics, Novosibirsk, Russia]
Ø바카라 먹튀Place : Physics Seminar Room (Science Bldg, 3-201)
Ø바카라 먹튀Date & Time :바카라 먹튀Aug, 20 (Thu), 15:00 ~ 16:00 pm
Abstract
The talk is devoted to the results of the experimental study of a principally new 2D electron system: a two-dimensional (2D) semimetal,바카라 먹튀recently바카라 먹튀realized for바카라 먹튀the first time in quantum wells (QWs) on basis of zero gap semiconductor HgTe. It is shown that this 2D semimetal exists in바카라 먹튀wide바카라 먹튀(thickness of 18 nm – 21 nm) undoped HgTe QWs with바카라 먹튀the바카라 먹튀reduced바카라 먹튀symmetry바카라 먹튀surfaces (such as (013)바카라 먹튀and (112)).바카라 먹튀Because바카라 먹튀of바카라 먹튀an inverted band structure and respectively the peculiar properties of바카라 먹튀size바카라 먹튀quantization바카라 먹튀in바카라 먹튀these바카라 먹튀QWs바카라 먹튀the overlap of a conductance band (with the bottom in the centre of Brillouin zone) and valence band (with the few maximums in its side points) arises. Its value is about 10 meV. So due to this overlap we have the true 2D semimetal similar to that of classical 3D semimetals such as Bi, Sb or As and there is the opportunity to realize the simultaneous existence of an equilibrium gas or liquid of 2D electrons and 2D holes.바카라 먹튀Moreover by means of the field effect transistor structure fabricated on the basis of QW we are바카라 먹튀able바카라 먹튀by바카라 먹튀means바카라 먹튀of simple changing of바카라 먹튀the바카라 먹튀gate바카라 먹튀voltage,바카라 먹튀firstly,바카라 먹튀to바카라 먹튀realize바카라 먹튀and바카라 먹튀study바카라 먹튀transition바카라 먹튀2D바카라 먹튀electron바카라 먹튀metal – 2D semimetal – 2D hole metal and, secondly,바카라 먹튀2D semimetallic바카라 먹튀state with any ratio between the densities바카라 먹튀of 2D electrons (Ns) and 2D holes (Ps). So a lot of new interesting properties caused by their바카라 먹튀simultaneous existence have been observed. These are: 1) sign-variable Hall effect and positive magnetoresistance; 2) electron바카라 먹튀mobility바카라 먹튀jump바카라 먹튀due바카라 먹튀to바카라 먹튀hole바카라 먹튀screening바카라 먹튀of바카라 먹튀electron바카라 먹튀scattering바카라 먹튀by바카라 먹튀impurities, 3)바카라 먹튀anomalous temperature dependence of 2D semimetal resistance because of electron scattering by heavy holes. It is likely this effect is the first clear demonstration of the바카라 먹튀direct바카라 먹튀influence바카라 먹튀of바카라 먹튀a바카라 먹튀particle-particle바카라 먹튀inelastic Landau scattering on metal resistance and correspondingly of Pauli exclusion바카라 먹튀principal.바카라 먹튀But바카라 먹튀the바카라 먹튀most exiting opportunity appearing due to realization of 2D semimetal is to carry out바카라 먹튀the바카라 먹튀direct바카라 먹튀experimental observation of excitonic insulator (EI) state predicted almost fifty years ago by one바카라 먹튀of바카라 먹튀the바카라 먹튀greatest바카라 먹튀20 century condense matter physicists sir Nevill Mott. In 1961 he considered a semimetal and assumed that the Coulomb interaction between electrons and holes have to lead to the formation of their bound바카라 먹튀state and a semimetal should become an insulator. It is surprising but till now this very interesting and important transition has not been directly observed. The main reason of this situation is that till the last바카라 먹튀time바카라 먹튀there was absent the system in which this transition could be realized and then바카라 먹튀directly바카라 먹튀fixed바카라 먹튀by바카라 먹튀resistance measurement. Conventional tree-dimensional semimetal such as Bi or Sb did바카라 먹튀not바카라 먹튀fit바카라 먹튀because바카라 먹튀of바카라 먹튀the absence of the simple procedure to change the density of electron and holes. So in our 2D semimetal the EI state induced by magnetic field is found. It arises between electron-like and hole-like quantum Hall liquid states at the point Ns = Ps and near it. It바카라 먹튀is바카라 먹튀shown바카라 먹튀that바카라 먹튀the바카라 먹튀transition바카라 먹튀metal – EI바카라 먹튀is바카라 먹튀similar바카라 먹튀to superconductor-normal metal transition and described by BCS (Bardeen-Coopper-Schrieffer)-scenario: up to the critical temperature Tc ≈ 1 K no temperature dependence of the바카라 먹튀transport바카라 먹튀and바카라 먹튀capacitance response of the system is바카라 먹튀observed바카라 먹튀but just바카라 먹튀below바카라 먹튀this바카라 먹튀temperature바카라 먹튀the바카라 먹튀strong바카라 먹튀insulator바카라 먹튀behavior characterizing by the gap of about few Kelvins appears.
Contact Person : Prof. Hu-Jong Lee(054-279-2072,바카라 먹튀hjlee@postech.ac.kr)
"
-2.gif)
Login
