Three terminal capacitance technique for magnetostriction and thermal expansion measurements

TL;DR

This paper introduces a versatile capacitance-based instrument capable of measuring magnetostriction and thermal expansion in various samples from room temperature down to 4 K within high magnetic fields up to 12 T.

Contribution

It presents a novel three-terminal capacitance technique with enhanced sensitivity and applicability to small, large, and thin film samples for magnetostriction and thermal expansion measurements.

Findings

Achieved sensitivity of 0.5 Angstrom for measurements.

Successfully measured magnetostriction of MgB2 and thermal expansion of specific crystals.

Demonstrated applicability to thin films and irregularly shaped samples.

Abstract

An instrument has been constructed to measure a large range of magnetostriction and thermal expansion between room temperature and 4 K in a superconductive split-coil magnet, that allows investigation in magnetic fields up to 12 T. The very small bulk samples (up to 1 mm in size) as well as big ones (up to 13 mm) of the irregular form can be measured. The possibility of magnetostriction investigation in thin films is shown. A general account is given of both electrical and the mechanical aspects of the design of capacitance cell and their associated electronic circuitry. A simple lever device is proposed to increase the sensitivity twice. The resulting obtained sensitivity can be 0.5 Angstrom. The performance of the technique is illustrated by some preliminary measurements of the magnetostriction of superconducting MgB2, thermal expansion of (La0.8Ba0.2)0.93MnO3 single crystal and magnetoelastic behavior of the Ni/Si(111) and La0.7Sr0.3CoO3/SAT0.7CAT0.1LA0.2(001) cantilevers.