Capacitive detection of magnetostriction, dielectric constant, and magneto-caloric effects in pulsed magnetic fields
Capacitive detection of magnetostriction, dielectric constant, and magneto-caloric effects in pulsed magnetic fields
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DOI：
10.1063/5.0010753
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发表时间：
2020-10-01
影响因子：
1.6
通讯作者：
Tokunaga, Masashi
中科院分区：
文献类型：
--
作者：
Miyake, Atsushi;Mitamura, Hiroyuki;Tokunaga, Masashi
我们报告了一种电容测量系统的开发，该系统允许在高达61 t的脉冲磁场中测量电容。通过使用该系统，可以在脉冲磁场条件下研究各种物理量的磁场响应，如磁致伸缩，磁场诱导的复介电常数变化和磁热效应。在这里，我们检验了我们的系统在脉冲磁体中研究这些磁场诱导现象的有效性。对于磁致伸缩测量，可以通过粘在试样上的两个对齐电极和膨胀计之间的电容变化来测量试样的磁致伸缩。我们证明了通过磁致伸缩信号精确检测半金属铋中的谷极化，其分辨率优于相对长度变化的10（-6）。对于磁场诱导的复介电常数变化，我们成功地观察到多铁质Pb(TiO)Cu4(PO4)4中明显的介电异常伴随着磁/磁电相变。为了测量磁热效应，用电容温度计验证了Gd3Ga5O12的磁场引起的样品温度变化，该温度变化由非磁性铁电化合物KTa1-xNbxO3 （x = 0.02）制成，其电容几乎与场无关。这些结果表明，我们的电容测量系统是研究脉冲磁场中难以检测到的各种磁场感应现象的一个很有前途的工具。
We report on the development of a capacitance measuring system that allows measurements of capacitance in pulsed magnetic fields up to 61 T. By using this system, magnetic-field responses of various physical quantities, such as 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)Cu4(PO4)4. For the measurement of magneto-caloric effect, a magnetic-field-induced change in sample temperature was verified for Gd3Ga5O12 with a capacitance thermometer made of a non-magnetic ferroelectric compound KTa1-xNbxO3 (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.