Home > 게시판 > 세미나
아래와 같이 콜로퀴움을 개최하오니 많이 참석해 주시기 바랍니다.
4시 20분부터 제1과학관 31214 e+강의실에서 다과를 준비하오니 많은 참석 부탁드립니다.
Title: Local electronic structures of stacking grain boundary in bilayer graphene
Speaker: Prof. Gunn Kim (Department of Physics & Astronomy, Sejong University)
Date & Time: Sep. 30 (Wed.) 2015, 4:30 PM
Place: Natural Science 1, Room No. 31214
Abstract: Gap opening is possible in bilayer graphene (BLG), thus making it a very promising material that overcomes graphene’s key limitation while retaining many of its interesting properties. For example, massive Dirac fermions in BLG exhibit a band gap tunable by applying a transverse electric field (E field); this has been demonstrated by optical and electrical transport measurements using dual-gated devices. However, these measurements leave a couple of unsolved problems: (i) the origin of unexpectedly small transport gaps that are 2 orders of magnitude smaller than optical gaps and (ii) the origin of anomalous low-temperature (< 2 K) transport behaviors dominated by hopping between localized midgap states, presumably induced from disorder or defects.
Recent experiments have revealed complex configurations in BLG, including various stacking domains induced by rotational faults and soliton formation. While AB stacking is energetically most favorable, the non-ABstacking region can be stabilized by a minute twist and the stacking boundary. The local stacking configuration is strongly coupled to its electronic structure and its response to an external E field. Therefore, it is critically important, fundamentally and practically, to understand the observed complex stacking configurations and their impact on the overall electronic properties.
In this talk, I will present gap-opening properties of BLG near the high-symmetry stackings (AA, AA’, and AB), under an applied E field. We establish a phase diagram for the stacking-dependent gap openings and further identify grain boundaries containing non-AB stackings as a source for high-density midgap states even under a strong E field. Our findings offer insight to understanding the intrinsic transport properties of BLG.
Within density functional theory, our calculations adopt the Perdew-Burke-Ernzerhof version of the exchange-correlation functional and the projector augmented wave method for ionic potentials. We obtain interlayer distances between 3.25 (AB) and 3.45 A (AA) with van der Waals correction. To ensure an accurate band gap, the 2D DFT band structure near the K point is interpolated by using maximally localized Wannier functions. Effective Hamiltonians are constructed with the obtained hopping parameters truncated to the first-nearest-interlayer hopping.
|공지||<12/8(Thu.) 11:00am>노벨상 소개 강연 - 2016년 노벨 물리학상: 위상 응집 물리의 탄생||2016.11.28||1091381|
|176||<6/5> 물리학도가 증권가로 간 까닭은...||2013.05.29||70417|
|175||<5/29> Study on the electronic interactions in solids under high magnetic fields||2013.05.23||93112|
|174||<5/22> Computer-based Mathematical Analysis and Applications to Physics (컴퓨터 기반 수리해석과 물리학에의 응용)||2013.05.15||162554|
|173||<5/15> Quantum Critical Superconductivity||2013.05.09||71720|
|172||<5/8> Complex Networks: Through the 3D Looking Glass||2013.05.02||88777|
|171||<5/1> Entanglement and topological order in 1D and 2D systems||2013.04.18||118373|
|170||<4/17> Probing Stellar Explosions with Radioactive Beams*||2013.04.10||96587|
|169||<4/10> Mapulation of spins in organic compounds||2013.04.03||101585|
|168||<4/3> 내 안의 파장을 바꿔라!||2013.03.29||67537|
|167||<3/27> Proximity effects and low dimensional superconductivity of Pb nano-islands||2013.03.21||86807|
|166||<3/20> 빛 : 우주의 신비를 푸는 열쇠||2013.03.14||70720|
|165||<3/13> Quantum computing using solid state nano-devices||2013.03.08||68834|
|164||2013학년도 1학기 콜로퀴움 일정||2013.02.19||72550|
|163||<12/12> 자성체의 스커미온 동역학||2012.12.06||72877|
|162||<12/5> 과학용어와 의학용어에 숨겨진 이야기||2012.11.28||72362|
|161||<11/28> 별이 빛나는 밤에…||2012.11.22||71662|
|160||<11/21> 복잡 산화물 이종접합 및 다강체 연구(Complex oxide heterostructures and multiferroics)||2012.11.15||97180|
|159||<11/14> Next Generation LED||2012.11.08||68314|
|158||<11/7> Two- and three- body problems in classic and quantum mechanics||2012.10.29||86310|
|157||<10/31> Large-Scale Quantitative Analysis of Painting Arts||2012.10.18||212452|