相关论文: Evidence for Skyrmion crystallization from NMR rel…
The nuclear spin relaxation rate (1/$T_1$) is measured for GaAs two-dimensional electron systems in the quantum Hall regime with an all-electrical technique for agitating and probing the nuclear spins. A "tilted plateau" feature is observed…
Near to filling fraction $\nu=1$, the quantum Hall ferromagnet contains multiple Skyrmion spin excitations. This multi-Skyrmion system has a tremendously rich quantum-critical structure. This is simplified when Skyrmions are pinned by…
A nuclear magnetic resonance (NMR) study is reported of multiple (30) Al$_{0.13}$Ga$_{0.87}$As quantum well (QW) sample near the Landau level filling factor $\nu =1$. In these Al$_{0.13}$Ga$_{0.87}$As QWs the effective $g$ factor is nearly…
The transition from partial to complete spin polarization of two-dimensional electrons at half filling of the lowest Landau level has been studied using resistively-detected nuclear magnetic resonance (RDNMR). The nuclear spin-lattice…
The Knight shift and the nuclear spin-lattice relaxation rate 1/T1 of Ga-71 nuclei are measured in GaAs quantum wells at Landau level filling factor nu = 1/2 using optically pumped NMR. The temperature dependences of these data are compared…
The study of nuclear magnetic resonance and nuclear spin-lattice relaxation was conducted in an asymmetrically doped to $n\sim1.8\times10^{11}$ cm$^{-2}$ 16 nm AlAs quantum well grown in the $[001]$-direction. Dynamic polarization of…
The ground state of a two-dimensional electron gas at Landau level filling factors near $\nu =1$ is a Skyrme crystal with long range order in the positions and orientations of the topologically and electrically charged elementary…
We report on the numerical study of the relaxation rates of nuclear spins coupled through the hyperfine interaction to a two dimensional electron gas (2DEG) at magnetic fields corresponding to both fractional and integral Landau level (LL)…
A room temperature nuclear magnetic resonance force microscope (MRFM), fitted in a $^1$Tesla electromagnet, is used to measure the nuclear spin relaxation of $^1$H in a micron-size (70ng) crystal of ammonium sulfate. NMR sequences,…
Dirac semimetals provide a new platform for the quantum Hall effect at low magnetic fields. In the presence of strong spin-orbit coupling, a spin-split Landau level is expected to enhance the bulk quasiparticle excitation. Here we report…
We investigate interactions between electrons and nuclear spins by using the resistance (Rxx) peak which develops near filling factor n = 2/3 as a probe. By temporarily tuning n to a different value, ntemp, with a gate, the Rxx peak is…
Optically pumped nuclear magnetic resonance (OPNMR) measurements were performed in two different electron-doped multiple quantum well samples near the fractional quantum Hall effect ground state nu=1/3. Below 0.5K, the spectra provide…
At Landau level filling factors near nu =1, quantum Hall ferromagnets form a Skyrme crystal state with quasi-long-range translational and non-collinear magnetic order. We develop an effective low energy theory which explains the presence in…
We study the spin dynamics in a high-mobility two-dimensional electron gas confined in a GaAs/AlGaAs quantum well. An unusual magnetic field dependence of the spin relaxation is found: as the magnetic field becomes stronger, the spin…
Spin textures arise in the effective action approach to the quantum Hall effect. Up to now these textures, also called Skyrmions, have been mainly studied using approximations. Studies of its finite density form, the crystal, have been…
We investigate the electron spin states in the bilayer quantum Hall system at total Landau level filling factor nu =2 exploiting current-pumped and resistively detected NMR. The measured Knight shift, KS, of 75As nuclei reveals continuous…
The nuclear-spin-relaxation rate 1/T_1 has been measured in a bilayer electron system at and around total Landau level filling factor nu =1. The measured 1/T_1, which probes electron spin fluctuations, is found to increase gradually from…
This study examines the spin-lattice relaxation rate of Mn$^{2+}$ ions in strained diluted magnetic semiconductor (Cd,Mn)Te/(Cd,Mg)Te quantum wells using the optically detected magnetic resonance (ODMR) technique. By adjusting the magnesium…
A coherent superposition of many nuclear spin states can be prepared and manipulated via the hyperfine interaction with the electronic spins by varying the Landau level filling factor through the gate voltage in appropriately designed…
We report tilted-field magnetotransport measurements of two-dimensional electron systems in a 200 Angstrom-wide Al(0.13)Ga(0.87)As quantum well. We extract the energy gap for the quantum Hall state at Landau level filling \nu =1 as a…