scholarly journals Bilayer graphene under pressure: Electron-hole symmetry breaking, valley Hall effect, and Landau levels

2016 ◽  
Vol 93 (23) ◽  
Author(s):  
F. Munoz ◽  
H. P. Ojeda Collado ◽  
Gonzalo Usaj ◽  
Jorge O. Sofo ◽  
C. A. Balseiro
Keyword(s):  
Symmetry Breaking ◽  
Hall Effect ◽  
Bilayer Graphene ◽  
Landau Levels ◽  
Electron Hole ◽  
Valley Hall Effect

scholarly journals Ultrafast non-excitonic valley Hall effect in MoS2/WTe2 heterobilayers

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jekwan Lee ◽  
Wonhyeok Heo ◽  
Myungjun Cha ◽  
Kenji Watanabe ◽  
Takashi Taniguchi ◽  
...  
Keyword(s):  
Hall Effect ◽  
Quantitative Information ◽  
Exciton Energy ◽  
Electron Hole ◽  
Kerr Rotation ◽  
Polarized Electrons ◽  
Spatially Resolved ◽  
Long Valley ◽  
Bound Electron ◽  
Valley Hall Effect

AbstractThe valley Hall effect (VHE) in two-dimensional (2D) van der Waals (vdW) crystals is a promising approach to study the valley pseudospin. Most experiments so far have used bound electron-hole pairs (excitons) through local photoexcitation. However, the valley depolarization of such excitons is fast, so that several challenges remain to be resolved. We address this issue by exploiting a unipolar VHE using a heterobilayer made of monolayer MoS2/WTe2 to exhibit a long valley-polarized lifetime due to the absence of electron-hole exchange interaction. The unipolar VHE is manifested by reduced photoluminescence at the MoS2 A exciton energy. Furthermore, we provide quantitative information on the time-dependent valley Hall dynamics by performing the spatially-resolved ultrafast Kerr-rotation microscopy; we find that the valley-polarized electrons persist for more than 4 nanoseconds and the valley Hall mobility exceeds 4.49 × 103 cm2/Vs, which is orders of magnitude larger than previous reports.

scholarly journals Electron-hole asymmetric integer and fractional quantum Hall effect in bilayer graphene

Science ◽  
2014 ◽  
Vol 345 (6192) ◽  
pp. 55-57 ◽  
Author(s):  
A. Kou ◽  
B. E. Feldman ◽  
A. J. Levin ◽  
B. I. Halperin ◽  
K. Watanabe ◽  
...  
Keyword(s):  
Hall Effect ◽  
Quantum Hall Effect ◽  
Quantum Hall ◽  
Bilayer Graphene ◽  
Fractional Quantum Hall Effect ◽  
Many Body ◽  
Electron Hole ◽  
Fractional Quantum ◽  
Fractional Quantum Hall ◽  
Lowest Landau Level

The nature of fractional quantum Hall (FQH) states is determined by the interplay between the Coulomb interaction and the symmetries of the system. The distinct combination of spin, valley, and orbital degeneracies in bilayer graphene is predicted to produce an unusual and tunable sequence of FQH states. Here, we present local electronic compressibility measurements of the FQH effect in the lowest Landau level of bilayer graphene. We observe incompressible FQH states at filling factors ν = 2p + 2/3, with hints of additional states appearing at ν = 2p + 3/5, where p = –2, –1, 0, and 1. This sequence breaks particle-hole symmetry and obeys a ν → ν + 2 symmetry, which highlights the importance of the orbital degeneracy for many-body states in bilayer graphene.

Valley Hall Effect in Bilayer Graphene with Electrically Broken Inversion Symmetry

2016 ◽  
Author(s):  
Y. Shimazaki ◽  
M. Yamamoto ◽  
I.V. Borzenets ◽  
K. Watanabe ◽  
T. Taniguchi ◽  
...  
Keyword(s):  
Hall Effect ◽  
Bilayer Graphene ◽  
Inversion Symmetry ◽  
Valley Hall Effect

Inversion Symmetry Breaking Induced Valley Hall Effect in Multilayer WSe2

ACS Nano ◽  
2019 ◽  
Vol 13 (8) ◽  
pp. 9325-9331 ◽  
Author(s):  
Hongming Guan ◽  
Ning Tang ◽  
Hao Huang ◽  
Xiaoyue Zhang ◽  
Meng Su ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Hall Effect ◽  
Inversion Symmetry ◽  
Valley Hall Effect

scholarly journals Chemical potential and quantum Hall ferromagnetism in bilayer graphene

Science ◽  
2014 ◽  
Vol 345 (6192) ◽  
pp. 58-61 ◽  
Author(s):  
Kayoung Lee ◽  
Babak Fallahazad ◽  
Jiamin Xue ◽  
David C. Dillen ◽  
Kyounghwan Kim ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Chemical Potential ◽  
Hexagonal Boron Nitride ◽  
Quantum Hall ◽  
Bilayer Graphene ◽  
Zero Magnetic Field ◽  
High Magnetic Fields ◽  
Complex Interplay ◽  
Electron Hole ◽  
Quantum Hall State

Bilayer graphene has a distinctive electronic structure influenced by a complex interplay between various degrees of freedom. We probed its chemical potential using double bilayer graphene heterostructures, separated by a hexagonal boron nitride dielectric. The chemical potential has a nonlinear carrier density dependence and bears signatures of electron-electron interactions. The data allowed a direct measurement of the electric field–induced bandgap at zero magnetic field, the orbital Landau level (LL) energies, and the broken-symmetry quantum Hall state gaps at high magnetic fields. We observe spin-to-valley polarized transitions for all half-filled LLs, as well as emerging phases at filling factors ν = 0 and ν = ±2. Furthermore, the data reveal interaction-driven negative compressibility and electron-hole asymmetry in N = 0, 1 LLs.

scholarly journals Instability of the marginal commutative model of tunneling centers interacting with a metallic environment: Role of the electron-hole symmetry breaking

1997 ◽  
Vol 56 (20) ◽  
pp. 12947-12960 ◽  
Author(s):  
A. Zawadowski ◽  
G. Zaránd ◽  
P. Nozières ◽  
K. Vladár ◽  
G. T. Zimányi
Keyword(s):  
Symmetry Breaking ◽  
Electron Hole ◽  
Tunneling Centers

Evidence of electron-hole symmetry breaking in poly(p-phenylene vinylene)

2003 ◽  
Vol 68 (19) ◽  
Author(s):  
M. Baïtoul ◽  
J. Wéry ◽  
S. Lefrant ◽  
E. Faulques ◽  
J-P. Buisson ◽  
...  
Keyword(s):  
Symmetry Breaking ◽  
Phenylene Vinylene ◽  
Electron Hole

Photonic spin Hall effect in twisted bilayer graphene

2021 ◽  
Author(s):  
Zefeng Chen ◽  
HongWei Yang ◽  
Yihong Xiao ◽  
Jintao Pan ◽  
Yu Xia ◽  
...  
Keyword(s):  
Hall Effect ◽  
Bilayer Graphene ◽  
Spin Hall Effect ◽  
Twisted Bilayer Graphene
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