Magnetocapacitance oscillations and thermoelectric effect in a two-dimensional electron gas irradiated by microwaves

A. D. Levin, G. M. Gusev, O. E. Raichev, Z. S. Momtaz, and A. K. Bakarov
Phys. Rev. B 94, 045313 – Published 21 July 2016

Abstract

To study the influence of microwave irradiation on two-dimensional electrons, we apply a method based on capacitance measurements in GaAs quantum well samples where the gate covers a central part of the layer. We find that the capacitance oscillations at high magnetic fields, caused by the oscillations of thermodynamic density of states, are not essentially modified by microwaves. However, in the region of fields below 1 T, we observe another set of oscillations, with the period and the phase identical to those of microwave-induced resistance oscillations. The phenomenon of microwave-induced capacitance oscillations is explained in terms of violation of the Einstein relation between conductivity and the diffusion coefficient in the presence of microwaves, which leads to a dependence of the capacitor charging on the anomalous conductivity. We also observe microwave-induced oscillations in the capacitive response to periodic variations of external heating. These oscillations appear due to the thermoelectric effect and are in antiphase with microwave-induced resistance oscillations because of the Corbino-like geometry of our experimental setup.

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  • Received 10 May 2016
  • Revised 20 June 2016

DOI:https://doi.org/10.1103/PhysRevB.94.045313

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

A. D. Levin1, G. M. Gusev1, O. E. Raichev2, Z. S. Momtaz1, and A. K. Bakarov3,4

  • 1Instituto de Física da Universidade de São Paulo, 135960-170 São Paulo, SP, Brazil
  • 2Institute of Semiconductor Physics, NAS of Ukraine, Prospekt Nauki 41, 03028 Kiev, Ukraine
  • 3Institute of Semiconductor Physics, Novosibirsk 630090, Russia
  • 4Novosibirsk State University, Novosibirsk 630090, Russia

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Issue

Vol. 94, Iss. 4 — 15 July 2016

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