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

Atsushi Miyake; Hiroyuki Mitamura; Shiro Kawachi; Masashi Tokunaga; Kenta Kimura; Tsuyoshi Kimura; Takumi Kihara; Makoto Tachibana

doi:10.1063/5.0010753

arXiv · 2009.02870

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

Atsushi Miyake·Hiroyuki Mitamura·Shiro Kawachi·Masashi Tokunaga·Kenta Kimura·Tsuyoshi Kimura·Takumi Kihara·Makoto Tachibana

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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.

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Atsushi Miyake, Hiroyuki Mitamura, Shiro Kawachi, Masashi Tokunaga, Kenta Kimura, Tsuyoshi Kimura, Takumi Kihara, Makoto Tachibana. 2020-09-07. Capacitive detection of magnetostriction, dielectric constant, and magneto-caloric effects in pulsed magnetic fields. https://doi.org/10.1063/5.0010753

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