Probing Electron Interactions in a Two-Dimensional System by Quantum Magneto-Oscillations

Abstract

We have experimentally studied the renormalized effective mass m* and Dingle temperature T_D in two spin subbands with essentially different electron populations. Firstly, we found that the product (m*T_D) that determines damping of quantum oscillations, to the first approximation, is the same in the majority and minority subbands even at the spin polarization degree as high as 66\%. This result confirms the theoretical predictions that the interaction takes place at high energies ~ E_F rather than within a narrow strip of energies E_F\pm k_BT. Secondly, to the next approximation, we revealed a difference in the damping factor of the two spin subbands, which causes skewness of the oscillation lineshape. In the absence of the in-plane magnetic field, the damping factor (m*T_D) is systematically smaller in the spin-majority subband. The difference, quantified with the skew factor γ= (T_{D\downarrow}-T_{D\uparrow})/2T_{D0} can be as large as 20%. The skew factor tends to decrease as B_\parallel or temperature grow, or perpendicular field decreases; for low electron densities and high in-plane fields the skew factor even changes sign. Finally, we compared the temperature and magnetic field dependencies of the magneto-oscillations amplitude with predictions of the interaction correction theory, and found, besides some qualitative similarities, several quantitative and qualitative differences. To explain qualitatively our results, we suggested an empirical model that assumes the existence of easily magnetized triplet scatterers on the Si/SiO_2 interface.

20 pages, 21 figures

References in corpus (7)

• Metal-insulator transition in two-dimensional electron systems
• Measurements of the density-dependent many-body electron mass in 2D GaAs/AlGaAs Heterostructures
• Spin-independent origin of the strongly enhanced effective mass in a dilute 2D electron system
• Thermodynamic density of states of two-dimensional GaAs systems near the apparent metal-insulator transition
• Spin-Droplet State of an Interacting 2D Electron System
• Nonlinear screening and percolative transition in a two-dimensional electron liquid
• Magnetotransport in disordered delta-doped heterostructures

Cited by in corpus (1)

• Two dimensional electrons in (100) oriented silicon field effect structures in the region of low concentrations and high mobilities