Capacitive detection of magnetostriction, dielectric constant, and magneto-caloric effects in pulsed magnetic fields

TL;DR

This paper introduces a capacitance measurement system capable of detecting various magnetic-field-induced phenomena, such as magnetostriction, dielectric changes, and magneto-caloric effects, in pulsed magnetic fields up to 61 T, enabling new insights into these effects.

Contribution

The paper presents a novel capacitance measurement system optimized for pulsed magnetic fields, allowing precise detection of magnetostriction, dielectric anomalies, and magneto-caloric effects in challenging high-field conditions.

Findings

Detected valley polarization in bismuth with high resolution

Observed dielectric anomalies during phase transitions in multiferroic Pb(TiO)Cu4(PO4)4

Verified magneto-caloric effect in Gd3Ga5O12 using a capacitance thermometer

Abstract

We report on the development of a capacitance measuring system which allows measurements of capacitance in pulsed magnetic fields up to 61~T. By using this system, magnetic-field responses of various physical quantities such magnetostriction, magnetic-field-induced change in complex dielectric constant, and magneto-caloric effect can be investigated in pulsed-magnetic-field conditions. Here, we examine the validity of our system for investigations of these magnetic-field-induced phenomena in pulse magnets. For the magnetostriction measurement, magnetostriction of a specimen can be measured through a change in the capacitance between two aligned electrodes glued on the specimen and a dilatometer. We demonstrate a precise detection of valley polarization in semimetallic bismuth through a magnetostriction signal with a resolution better than 10$^{-6}$ of the relative length change. For the magnetic-field-induced change in complex dielectric constant, we successfully observed clear dielectric anomalies accompanied by magnetic/magnetoelectric phase transitions in multiferroic Pb(TiO)Cu$_4$(PO$_4$)$_4$. For the measurement of magneto-caloric effect, a magnetic-field-induced change in sample temperature was verified for Gd$_3$Ga$_5$O$_{12}$ with a capacitance thermometer made of a non-magnetic ferroelectric compound KTa$_{1-x}$Nb$_x$O$_3$ ($x$ = 0.02) whose capacitance is nearly field-independent. These results show that our capacitance measuring system is a promising tool to study various magnetic-field-induced phenomena which have been difficult to detect in pulsed magnetic fields.