Magnetic anisotropy and de Haas - van Alphen oscillations in a Bi microwire array studied via cantilever magnetometry at low temperatures

TL;DR

This study investigates the magnetic anisotropy and quantum oscillations in a Bi microwire array at low temperatures, revealing strong directional dependence and electron-dominated responses using cantilever magnetometry.

Contribution

It demonstrates the use of cantilever magnetometry to observe de Haas-van Alphen oscillations and magnetic anisotropy in Bi microwire arrays at cryogenic temperatures.

Findings

Magnetic response is highly anisotropic, larger perpendicular to wire axis.

de Haas-van Alphen oscillations are clearly observed.

Light electrons dominate the magnetic response.

Abstract

We report measurements of the low temperature (T = 0.5 K) oscillatory magnetization in a high-density array of 50 micron diameter wires of polycrystalline Bi utilizing a high sensitivity silicon cantilever magnetometer. We find that the magnetic response is strongly anisotropic, being much larger for magnetic field perpendicular than for fields parallel to the wire-axis. We argue that this is a geometric effect caused by the large aspect ratio of the individual microwires in the array. The magnetic response of the microwires is dominated by the light electrons due to the larger cyclotron orbits in comparison with the heavier holes. We find that de Haas - van Alphen oscillations are easily resolved, and discuss the application of this technique to the study of Bi nanowire arrays.