Temperature dependence and mechanism of electrically detected ESR at theν=1filling factor of a two-dimensional electron system

Abstract

Electrically detected electron spin resonance (EDESR) signals were acquired as a function of temperature in the 0.3-4.2 K temperature range in a AlGaAs/GaAs multiple quantum well sample at the 1 ν = filling factor at 5.7 T. In the particular sample studied, the line width is approximately temperature independent, while the amplitude exhibits a maximum at about 2.2 K and vanishes with increased or decreased temperature. To explain the observed temperature dependence of the signal amplitude, the signal amplitude temperature dependence is calculated assuming a model based on heating. The model ascribes the resonant absorption of microwave power of the 2DES to the uniform mode of the electron spin magnetization where the elementary spin excitations at filling factor 1 ν = are taken to be spin waves, while the short wavelength spin wave modes serve as a heat sink for the absorbed energy. Due to the finite thermal conductance to the surroundings, the temperature of the 2DES spin wave system is increased, resulting in a thermal activation of the longitudinal magnetoconductance. The proposed heating model correctly predicts the location of the maximum in the experimentally observed temperature dependence of the EDESR amplitude. It also correctly predicts that the signal should vanish as the temperature is increased or decreased. The results of the present study demonstrate how experimental EDESR studies can, under appropriate conditions, provide data that can be used to discriminate between competing theories for the magnetic ordering and magnetic excitations of a 2DES in the regime of the quantum Hall effect.Introduction.

Electrically Detected Electron Spin Resonance in a High-Mobility Silicon Quantum Well

“…In the previous measurements on GaAs 2DESs at ν = odd, positive ∆ρ xx due to ESR have been reported [2,5]. Shown in Fig.…”

“…However, the origin of the resistivity change due to ESR absorption has not been established. In previous works performed on GaAs two-dimensional electron systems (2DESs) in high magnetic fields [2,3,4,5], the sign of the change ∆ρ xx in longitudinal resistivity ρ xx was found to be the same as that of the derivative of ρ xx with respect to temperature T and the effect of electron heating has not been excluded.For fabricating spintronics devices, silicon appears to be a very suitable host material. Addition to the compatibility with the fabrication technology of integrated circuits, it has the advantage of long electron spin relaxation times due to weak spin-orbit interactions and poor electron-nuclear spin (hyperfine) coupling.…”

Electron–nuclear double resonance and dynamic nuclear polarization in GaAs in the regime of the quantum Hall effect

“…Both samples were photolithographically patterned into a Hall bar with a 0.2 mm channel width and 1.5 mm probe contact separation of. The experiments described here were conducted with the sample immersed in 3 He using the same microwave source, cryostat and double-lockin detection method described previously [10].…”

“…However, the detection of electron spin flips by resonant absorption of microwaves in a direct band gap semiconductor QW or heterojunction is problematic due to the small electron slab volume and spin concentrations. On the other hand, longitudinal magnetoresistance detection (MD) affords the requisite selectivity and sensitivity for magnetic resonance spectroscopy in these systems [5][6][7][8][9][10]. MD is applicable in quantum Hall systems when the Fermi energy is situated near the middle of the spin gap.…”

“…MD has been applied to the study of a variety of phenomena, including the g-factor magnetic field dependence [7,8], the fractional QHE [8], and g-factor tuning in gated devices [9]. Recently, the temperature dependence and mechanism of magnetoresistance detection electron spin resonance (MDESR) has been explained by a model involving heating of the 2DES by the resonant deposition of microwave energy into the k ¼ 0 spin wave modes and the subsequent redistribution to ka0 modes by scattering processes, leading to dissociation of spin excitons [10]. The ability to indirectly detect NMR via MDESR [11,12] offers the possibility to correlate NMR and ESR transitions to transport properties.…”