相关论文: Phase Transition to Insulating State from Quantum …

We investigate the disorder-driven phase transition from a fractional quantum Hall state to an Anderson insulator using quantum entanglement methods. We find that the transition is signaled by a sharp increase in the sensitivity of a…

The average electron spin-polarization $\cal P$ of two-dimensional electron gas confined in $\rm GaAs/GaAlAs$ multiple quantum-wells was measured by nuclear magnetic resonance (NMR) near the fractional quantum Hall state with filling factor…

Exploring a backgated low density two-dimensional hole sample in the large $r_s$ regime we found a surprisingly rich phase diagram. At the highest densities, beside the $\nu=1/3$, 2/3, and 2/5 fractional quantum Hall states, we observe both…

We report on the dramatic evolution of the quantum Hall ferromagnet in the fractional quantum Hall regime at $\nu = 2/5$ filling. A large enhancement in the characteristic timescale gives rise to a dynamical transition into a novel…

We present a magnetization measurement probing the transition from a quantum Hall to insulating (QH-I) state for a two-dimensional electron gas in a disordered GaAs/AlGaAs heterostructure. Using a highly sensitive DC torque magnetometer, we…

Experiments suggest that nuclear spins play a significant role in the quantum Hall effect (QHE) near integer and fractional QHE spin transitions, but many of these phenomena still remain to be understood. Here we study theoretically the…

We study dynamic nuclear polarization (DNP) induced by breakdown of the fractional quantum Hall (FQH) effect. We find that voltage-current characteristics depend on current sweep rates at the quantum Hall states of Landau level filling…

We have observed an anomalous shift of the high field reentrant insulating phases in a two-dimensional electron system (2DES) tightly confined within a narrow GaAs/AlGaAs quantum well. Instead of the well-known transitions into the high…

We present dynamic nuclear polarization (DNP) in the simplest pseudospin quantum Hall ferromagnet (QHF) of an InSb two-dimensional electron gas with a large g factor using tilted magnetic fields. The DNP-induced amplitude change of a…

We have investigated the effect of unidirectional periodic potential modulation on the fractional quantum Hall (FQH) state at filling factors nu=5/3 and 4/3. For large enough modulation amplitude, we find that the resistivity minimum at…

We observe nuclear magnetic resonance (NMR) in the fractional quantum Hall regime at Landau level filling factor $\nu=2/3$ from simultaneous measurement of longitudinal resistance and photoluminescence (PL). The dynamic nuclear spin…

We study the \nu=5/2 even-denominator fractional quantum Hall effect (FQHE) over a wide range of magnetic (B) field in a heterojunction insulated gate field-effect transistor (HIGFET). The electron density can be tuned from n=0 to 7.6…

Fundamental insight into the nature of the quantum phase transition from a superconductor to an insulator in two dimensions, or from one plateau to the next or to an insulator in quantum Hall effect, has been revealed through the study of…

We measured the magnetoresistance of bilayer quantum Hall (QH) effects at the fractional filling factor $\nu =2/3$ by changing the total electron density and the density difference between two layers. Three different QH states were…

In magnetic topological insulators, a phase transition between a quantum anomalous Hall (QAH) and an Anderson localization phase can be triggered by the rotation of an applied magnetic field. Without the scattering paths along magnetic…

We report on an absolute measurement of the electronic spin polarization of the $\nu=1$ integer quantum Hall state. The spin polarization is extracted in the vicinity of $\nu=1$ (including at exactly $\nu=1$) via resistive NMR experiments…

Experiments on a nearly spin degenerate two-dimensional electron system reveals unusual hysteretic and relaxational transport in the fractional quantum Hall effect regime. The transition between the spin-polarized (with fill fraction $\nu =…

We have measured the magnetoresistance of a very low density and an extremely high quality two-dimensional hole system. With increasing magnetic field applied perpendicularly to the sample we observe the sequence of insulating, $\nu=1/3$…

Termination of the fractional quantum Hall states (FQHSs) and the emergence of Wigner crystal phases at very small Landau level filling factors ($\nu$) have been of continued interest for decades. Recently, in ultra-high-quality, dilute…

Using a combination of heat pulse and nuclear magnetic resonance techniques we demonstrate that the phase boundary separating the interlayer phase coherent quantum Hall effect at $\nu_T = 1$ in bilayer electron gases from the weakly coupled…