scholarly journals Partially spin-polarized quantum Hall effect in the filling factor range1/3<ν<2/5

2003 ◽  
Vol 67 (12) ◽  
Author(s):  
Chia-Chen Chang ◽  
Sudhansu S. Mandal ◽  
Jainendra K. Jain
Keyword(s):  
Hall Effect ◽  
Quantum Hall Effect ◽  
Filling Factor ◽  
Quantum Hall ◽  
Spin Polarized

scholarly journals Counter-propagating charge transport in the quantum Hall effect regime

Science ◽  
2019 ◽  
Vol 363 (6422) ◽  
pp. 54-57 ◽  
Author(s):  
Fabien Lafont ◽  
Amir Rosenblatt ◽  
Moty Heiblum ◽  
Vladimir Umansky
Keyword(s):  
Hall Effect ◽  
Quantum Hall Effect ◽  
Electron Gas ◽  
Quantum Hall ◽  
Charge Carriers ◽  
Perpendicular Magnetic Field ◽  
Quantum Hall Regime ◽  
Hall Regime ◽  
Spin Polarized ◽  
Conjugate States

The quantum Hall effect, observed in a two-dimensional (2D) electron gas subjected to a perpendicular magnetic field, imposes a 1D-like chiral, downstream, transport of charge carriers along the sample edges. Although this picture remains valid for electrons and Laughlin’s fractional quasiparticles, it no longer holds for quasiparticles in the so-called hole-conjugate states. These states are expected, when disorder and interactions are weak, to harbor upstream charge modes. However, so far, charge currents were observed to flow exclusively downstream in the quantum Hall regime. Studying the canonical spin-polarized and spin-unpolarized v = 2/3 hole-like states in GaAs-AlGaAs heterostructures, we observed a significant upstream charge current at short propagation distances in the spin unpolarized state.

scholarly journals Quantum parity Hall effect in Bernal-stacked trilayer graphene

2019 ◽  
Vol 116 (21) ◽  
pp. 10286-10290 ◽  
Author(s):  
Petr Stepanov ◽  
Yafis Barlas ◽  
Shi Che ◽  
Kevin Myhro ◽  
Greyson Voigt ◽  
...  
Keyword(s):  
Hall Effect ◽  
Quantum Hall Effect ◽  
Quantum Hall ◽  
Exchange Interactions ◽  
Mirror Reflection ◽  
Edge States ◽  
State Variables ◽  
Coulomb Interactions ◽  
Spin Polarized ◽  
Trilayer Graphene

The quantum Hall effect has recently been generalized from transport of conserved charges to include transport of other approximately conserved-state variables, including spin and valley, via spin- or valley-polarized boundary states with different chiralities. Here, we report a class of quantum Hall effect in Bernal- or ABA-stacked trilayer graphene (TLG), the quantum parity Hall (QPH) effect, in which boundary channels are distinguished by even or odd parity under the system’s mirror reflection symmetry. At the charge neutrality point, the longitudinal conductance σxx is first quantized to 4e2/h at a small perpendicular magnetic field B⊥, establishing the presence of four edge channels. As B⊥ increases, σxx first decreases to 2e2/h, indicating spin-polarized counterpropagating edge states, and then, to approximately zero. These behaviors arise from level crossings between even- and odd-parity bulk Landau levels driven by exchange interactions with the underlying Fermi sea, which favor an ordinary insulator ground state in the strong B⊥ limit and a spin-polarized state at intermediate fields. The transitions between spin-polarized and -unpolarized states can be tuned by varying Zeeman energy. Our findings demonstrate a topological phase that is protected by a gate-controllable symmetry and sensitive to Coulomb interactions.

INHOMOGENEITY OF ELECTRON LIQUID AND EFFECTS OF INTERLAYER COUPLING IN GaAs/AlGaAs SUPERLATTICES IN THE REGIME OF THE QUANTUM HALL EFFECT

2007 ◽  
Vol 21 (08n09) ◽  
pp. 1409-1413
Author(s):  
Y. A. PUSEP ◽  
F. E. G. GUIMARÃES ◽  
H. ARAKAKI ◽  
C. A. DE SOUZA ◽  
A. J. CHIQUITO
Keyword(s):  
Hall Effect ◽  
Quantum Hall Effect ◽  
Filling Factor ◽  
Quantum Hall ◽  
Interlayer Coupling ◽  
Integer Quantum Hall Effect ◽  
Weakly Coupled ◽  
Integer Quantum ◽  
Increasing Temperature ◽  
Partial Population

Formation of the electron state with the integer filling factor was studied by magneto-capacitance and magneto-photoluminescence measurements in weakly coupled GaAs/AlGaAs multilayers where quasi-two dimensional electrons revealed the integer Quantum Hall Effect. The disorder modulated compressibility of the quantized Hall phase with the filling factor ν=2 was determined. The incompressible fraction of this phase was shown to rapidly disappear with the increasing temperature. The quantized Hall phase of the weakly coupled multilayers was shown to emit the asymmetrical photoluminescence lines. We demonstrated that the observed asymmetry is caused by a partial population of the extended electron states formed in the quantized Hall conductor phase due to the disorder induced interlayer tunneling.

FRACTIONAL QUANTUM HALL EFFECT: CONSTRUCTION OF THE HARTREE–FOCK STATE BY USING TRANSLATIONAL COVARIANCE

1994 ◽  
Vol 08 (05) ◽  
pp. 529-579 ◽  
Author(s):  
R. FERRARI
Keyword(s):  
Magnetic Field ◽  
Hall Effect ◽  
Landau Level ◽  
Quantum Hall Effect ◽  
Filling Factor ◽  
Quantum Hall ◽  
Fractional Quantum Hall Effect ◽  
Fractional Quantum ◽  
Fractional Quantum Hall ◽  
Hartree Fock

The formalism introduced in a previous paper is used for discussing the Coulomb interaction of many electrons moving in two space-dimensions in the presence of a strong magnetic field. The matrix element of the Coulomb interaction is evaluated in the new basis, whose states are invariant under discrete translations (up to a gauge transformation). This paper is devoted to the case of low filling factor, thus we limit ourselves to the lowest Landau level and to spins all oriented along the magnetic field. For the case of filling factor νf = 1/u we give an Ansatz on the state of many electrons which provides a good approximated solution of the Hartree–Fock equation. For general filling factor νf = u′/u a trial state is given which converges very rapidly to a solution of the self-consistent equation. We generalize the Hartree–Fock equation by considering some correlation: all quantum states are allowed for the u′ electrons with the same translation quantum numbers. Numerical results are given for the mean energy and the energy bands, for some values of the filling factor (νf = 1/2, 1/3, 2/3, 1/4, 3/4, 1/5, 2/5, 3/5, 4/5). Our results agree numerically with the Charge Density Wave approach. The boundary conditions are shown to be very important: only large systems (degeneracy of Landau level over 200) are not affected by the boundaries. Therefore results obtained on small scale systems are somewhat unreliable. The relevance of the results for the Fractional Quantum Hall Effect is briefly discussed.

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