The manifestation of Fermi level oscillations in the magnetoresistance of HgTe quantum wells with a split spectrum

TL;DR

This study investigates Fermi level oscillations in HgTe quantum wells through magnetoresistance measurements, revealing unusual oscillation behaviors linked to spin-orbit split spectra and magnetic field effects.

Contribution

It provides experimental evidence of Fermi level oscillations in HgTe quantum wells and explains their origin through detailed measurements and numerical calculations.

Findings

Fermi level oscillations cause shifts in magnetoresistance oscillation patterns.

Unusual phase relationships observed in low magnetic fields.

Temperature-dependent measurements support the Fermi level oscillation hypothesis.

Abstract

Shubnikov-de Haas (SdH) oscillations and magneto-intersubband oscillations of magnetoresistance of structures with single HgTe quantum wells with a width of (10-18) nm have been experimentally studied. The spectrum of the conduction band in these structures is split by the spin-orbit interaction. This leads to beats of the SdH oscillations and the appearance of low-frequency magneto-intersubband oscillations. The mutual position of the antinodes of the SdH oscillations and the maxima of the magneto-interband oscillations is unusual -- in low magnetic fields it is directly opposite to the predictions of the theory. Measurements in high magnetic fields, in which the relative amplitude of the SdH oscillations becomes greater than 0.2-0.3, show a change in the relative position of the antinodes of the SdH oscillations and the maxima of low-frequency oscillations. Numerical calculations and additional measurements at different temperatures show that the observed effects are due to oscillations of the Fermi level in the magnetic field.