Related papers: Quantum-Hall activation gaps in graphene
We have studied the magnetotransport near Landau level filling factor $\nu = 1/2$ in a GaAs-Al0.3Ga0.7As square quantum well (width 35 nm) in magnetic field up to 42 T and in a temperature range between 50 mK and 1.5 K. In low temperatures…
It is known that $n$-degenerate Landau levels with the same spin-valley quantum number can be realized by $n$-layer graphene with rhombohedral stacking under magnetic field $B$. We find that the wave functions of degenerate Landau levels…
In a low-disorder two-dimensional electron system, when two Landau levels of opposite spin or pseudospin cross at the Fermi level, the dominance of the exchange energy can lead to a ferromagnetic, quantum Hall ground state whose gap is…
We present temperature-dependent magneto-transport experiments around the charge neutrality point in graphene and determine the amplitude of potential fluctuations $s$ responsible for the formation of electron-hole puddles. The experimental…
We derive an effective two-dimensional Hamiltonian to describe the low energy electronic excitations of a graphite bilayer, which correspond to chiral quasiparticles with a parabolic dispersion exhibiting Berry phase $2\pi$. Its…
Bilayer graphene exhibits a rich phase diagram in the quantum Hall regime, arising from a multitude of internal degrees of freedom, including spin, valley, and orbital indices. The variety of fractional quantum Hall states between filling…
The discrepancy between the theoretically calculated and experimentally measured activation gaps in quantum Hall effect has long been a puzzle. We revisit this issue in the context of the $\nu=1$ quantum Hall state, while also incorporating…
Since the ground-breaking discovery of the quantum Hall effect, half-quantized quantum Hall plateaus have been some of the most studied and sought-after states. Their importance stems not only from the fact that they transcend the composite…
Monolayer graphite films, or graphene, have quasiparticle excitations that can be described by 2+1 dimensional Dirac theory. We demonstrate that this produces an unconventional form of the quantized Hall conductivity $\sigma_{xy} = - (2…
We report on magnetospectroscopy of HgTe quantum wells in magnetic fields up to 45 T in temperature range from 4.2 K up to 185 K. We observe intra- and inter-band transitions from zero-mode Landau levels, which split from the bottom…
There is an increasing interest in the electronic properties of few layer graphene as it offers a platform to study electronic interactions because the dispersion of bands can be tuned with number and stacking of layers in combination with…
The fractional quantum Hall (FQH) effect is reported in a high mobility CdTe quantum well at mK temperatures. Fully-developed FQH states are observed at filling factor 4/3 and 5/3 and are found to be both spin-polarized ground state for…
Graphene enables precise carrier-density control via gating, making it an ideal platform for studying electronic interactions. However, sample inhomogeneities often limit access to the low-density regimes where these interactions dominate.…
Fabrication of devices made by isolated Graphene or Graphene-like single layers (such as h-BN) has opened up possibility of examining highly correlated states of electron systems in parts of their phase diagram that is impossible to access…
We have studied the $\nu=5/2$ fractional quantum Hall state in a density-tunable sample at extremely low electron densities. For the densities accessed in our experiment, the Landau level mixing parameter $\kappa$ spans the…
The nature of the state at low Landau-level filling factors has been a longstanding puzzle in the field of the fractional quantum Hall effect. While theoretical calculations suggest that a crystal is favored at filling factors $\nu\lesssim…
Quantum Hall effect in 1,2-layer graphene is analyzed. The transverse and longitudinal resistivity are found to be universal functions of the filling factor and temperature. At fixed magnetic field mode the magneto-transport problem is…
Breakdown of the quantum Hall effect (QHE) is commonly associated with an electric field approaching the inter Landau-level (LL) Zener field, ratio of the Landau gap and cyclotron radius. Eluded in semiconducting heterostructures, in spite…
A proposal of the existence of an {\em Anomalous} phase ($\mathcal{A}$ phase) [https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.056202 Das et al., Phys. Rev. Lett. 131, 056202 (2023)] at the experimental range of moderate…
We present magneto-Raman scattering studies of electronic inter Landau level excitations in quasi-neutral graphene samples with different strengths of Coulomb interaction. The band velocity associated with these excitations is found to…