國立虎尾科技大學 |

Understanding Correlated Insulating Ground States of Magic-Angle Twisted Bilayer Graphene.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Understanding Correlated Insulating Ground States of Magic-Angle Twisted Bilayer Graphene./
Author:	Soejima, Tomohiro.
Description:	1 online resource (129 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 85-03, Section: B.
Contained By:	Dissertations Abstracts International85-03B.
Subject:	Condensed matter physics. -
Online resource:	click for full text (PQDT)
ISBN:	9798380369190

Understanding Correlated Insulating Ground States of Magic-Angle Twisted Bilayer Graphene.
Soejima, Tomohiro.

Understanding Correlated Insulating Ground States of Magic-Angle Twisted Bilayer Graphene. - 1 online resource (129 pages)

Source: Dissertations Abstracts International, Volume: 85-03, Section: B.

Thesis (Ph.D.)--University of California, Berkeley, 2023.

Includes bibliographical references

When two layers of graphene are put on top of each another with a relative twist, their lattice mismatch gives rise to a moire pattern. When the twist angle is near 1.1 degrees, a so-called magic angle, the band structure of twisted bilayer graphene becomes extremely flat around the Fermi energy, enhancing the effect of electron-electron interaction. Remarkably, magic-angle twisted bilayer graphene (MATBG) becomes superconducting at low temperatures. The origin of this superconducting behavior remains elusive.Curiously, the superconducting behavior is usually accompanied by correlated insulating behavior in nearby parameter regions in the phase diagram. These correlated insulators cannot be described by non-interacting band theory, hinting at the importance of electron-electron interaction.In this thesis, we attempt to understand these correlated insulators by a combination of numerical and analytical techniques. On the numerical side, we will utilize the density-matrix renormalization group (DMRG) extensively to obtain the ground states of MATBG. Owing to the complexity of the problem, this required us to develop a non-trivial routine for encoding the Hamiltonian. We find that DMRG often reproduces the findings from Hartree-Fock simulations. On the analytical side, we aim to understand different symmetry-breaking states of MATBG. Based on symmetry analysis, we propose using scanning tunneling microscopy (STM) to distinguish between different candidate ground states, and test our analytical prediction using numerical simulation.Taken together, this thesis represents a significant step toward understanding the correlated insulating behavior of MATBG.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9798380369190Subjects--Topical Terms:

1148471
Condensed matter physics.
Subjects--Index Terms:

Strongly correlated electronsIndex Terms--Genre/Form:

554714
Electronic books.

Understanding Correlated Insulating Ground States of Magic-Angle Twisted Bilayer Graphene.
LDR:03112ntm a22003977 4500 001 1151856
005 20241118135844.5
006 m o d
007 cr mn ---uuuuu
008 250605s2023 xx obm 000 0 eng d
020 $a 9798380369190
035 $a (MiAaPQ)AAI30634847
035 $a AAI30634847
040 $a MiAaPQ $b eng $c MiAaPQ $d NTU
100 1 $a Soejima, Tomohiro. $3 1478693
245 1 0 $a Understanding Correlated Insulating Ground States of Magic-Angle Twisted Bilayer Graphene.
264 0 $c 2023
300 $a 1 online resource (129 pages)
336 $a text $b txt $2 rdacontent
337 $a computer $b c $2 rdamedia
338 $a online resource $b cr $2 rdacarrier
500 $a Source: Dissertations Abstracts International, Volume: 85-03, Section: B.
500 $a Advisor: Zaletel, Michael.
502 $a Thesis (Ph.D.)--University of California, Berkeley, 2023.
504 $a Includes bibliographical references
520 $a When two layers of graphene are put on top of each another with a relative twist, their lattice mismatch gives rise to a moire pattern. When the twist angle is near 1.1 degrees, a so-called magic angle, the band structure of twisted bilayer graphene becomes extremely flat around the Fermi energy, enhancing the effect of electron-electron interaction. Remarkably, magic-angle twisted bilayer graphene (MATBG) becomes superconducting at low temperatures. The origin of this superconducting behavior remains elusive.Curiously, the superconducting behavior is usually accompanied by correlated insulating behavior in nearby parameter regions in the phase diagram. These correlated insulators cannot be described by non-interacting band theory, hinting at the importance of electron-electron interaction.In this thesis, we attempt to understand these correlated insulators by a combination of numerical and analytical techniques. On the numerical side, we will utilize the density-matrix renormalization group (DMRG) extensively to obtain the ground states of MATBG. Owing to the complexity of the problem, this required us to develop a non-trivial routine for encoding the Hamiltonian. We find that DMRG often reproduces the findings from Hartree-Fock simulations. On the analytical side, we aim to understand different symmetry-breaking states of MATBG. Based on symmetry analysis, we propose using scanning tunneling microscopy (STM) to distinguish between different candidate ground states, and test our analytical prediction using numerical simulation.Taken together, this thesis represents a significant step toward understanding the correlated insulating behavior of MATBG.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2024
538 $a Mode of access: World Wide Web
650 4 $a Condensed matter physics. $3 1148471
650 4 $a Physical chemistry. $3 1148725
650 4 $a Materials science. $3 557839
653 $a Strongly correlated electrons
653 $a Superconductivity
653 $a Twisted bilayer graphene
653 $a Density-matrix
653 $a Scanning tunneling microscopy
655 7 $a Electronic books. $2 local $3 554714
690 $a 0611
690 $a 0794
690 $a 0494
710 2 $a ProQuest Information and Learning Co. $3 1178819
710 2 $a University of California, Berkeley. $b Physics. $3 1148718
773 0 $t Dissertations Abstracts International $g 85-03B.
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30634847 $z click for full text (PQDT)