A pulsed high magnetic field facility for electric polarization measurements
A pulsed high magnetic field facility for electric polarization measurements
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DOI：
10.7498/aps.69.20191520
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发表时间：
2020-03
影响因子：
1
通讯作者：
Liu Wan-Xin;Chen Rui;Liu Yong-jie;Wang Jun-feng;Han Xiao-tao;Yang Ming
中科院分区：
文献类型：
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作者：
Liu Wan-Xin;Chen Rui;Liu Yong-jie;Wang Jun-feng;Han Xiao-tao;Yang Ming
多铁性材料具有铁磁、铁电或铁弹有序共存的特性，不仅在基础物理学方面，而且在潜在的应用方面都具有特殊的意义。多铁性材料，特别是那些具有磁驱动铁电性的材料的一个重要物理性质，被称为磁序和铁电序之间的强磁电耦合。外磁场可以直接与材料的自旋或磁矩相互作用，导致自发铁电性被抑制，在某些情况下，在更高的磁场中会产生场感生铁电性。根据交换相互作用，这些铁电相变可能发生在一个临界磁场高达几十特斯拉。因此，基于商用PPMS系统的标准电极化测量受到静电场强度的限制。脉冲磁场作为一种极端的实验条件，可以用来揭示多铁性材料中新的物理现象。由于脉冲持续时间短和涡流的影响，这种测量技术在脉冲强磁场下仍然是一个挑战，尽管近年来一些实验室已经开发了它。武汉国家强磁场中心是一个新建的脉冲磁场实验室。该实验站配备了许多测量仪器，如测量电输运，磁化，电子自旋共振，磁光和高压，这些仪器是在2014年底国家评估后建立的。最近，利用热释电技术，我们成功地构建了一个电极化测量系统的基础上，在WHMFC的大型设施。用1.25MJ的电容器组放电驱动的非破坏性磁体可产生高达60 T的脉冲磁场。通过调节充电能量和充电电压，脉冲持续时间可从4.3ms调节到10.8ms。在该装置上安装的氦-3低温系统可实现最低0.5K的温度。设计并制作了一种高精度旋转测头，测头的旋转角度范围为-5° ~ 185°，可进行角度相关性研究。通过10 kΩ的分流电阻检测热释电电流，并通过对热释电电流随时间的积分导出电极化。所得数据具有良好的准确性和质量，这有助于检测弱铁电相变的脉冲场与快速场扫描速率。本文详细介绍了该测量系统的测量方法、原理及其与静态场测量系统的比较。介绍了强磁场下磁电多铁性材料的研究进展。
Multiferroic materials, which exhibit the coexistence of ferromagnetic, ferroelectric, or ferroelastic orders, are of particular interest for not only fundamental physics but also potential applications. An important physical property of multiferroic materials, especially those with magnetically driven ferroelectricity, is known as a strong magnetoelectric coupling between the magnetic order and the ferroelectric order. The external magnetic fields can directly interact with spins or magnetic moments of the materials and lead the spontaneous ferroelectricity to be suppressed, and in some cases result in field-induced ferroelectricity in a higher field. Depending on the exchange interactions, these ferroelectric phase transitions may take place in a critical magnetic field as high as several tens of tesla. The standard electric-polarization measurement based on a commercial PPMS system is limited by the strength of the static field consequently. As an extremely experimental condition, pulsed magnetic fields can be used to reveal new physical phenomena in multiferroic materials. Due to the short pulse duration and the effect of eddy current, this measurement technique under pulsed high magnetic fields is still a challenge to date although a few laboratories have developed it in recent years. Wuhan National High Magnetic Field Center (WHMFC) of China is a newly built pulsed-field laboratory. This experimental station is equipped with the many measuring instruments such as for measuring electric transport, magnetization, electron spin resonance, magneto-optics, and high pressure, which were established after the national assessment at the end of 2014. Recently, using a pyroelectric technique we successfully constructed an electric-polarization measurement system based on the large-scaled facility at the WHMFC. The nondestructive magnet driven by discharging a 1.25 MJ capacitor bank can generate a pulsed field up to 60 T. By tuning the charging energy and voltages, the pulse duration time can be modulated from 4.3 ms to 10.8 ms. A helium-3 cryogenic system equipped on this facility can achieve a lowest temperature down to 0.5 K. A high-precision rotation probe is designed and fabricated with angle varying from –5° to 185° for an angular-dependent study. The pyroelectric current is detected by a shunt resistor of 10 kΩ and the electric polarization is derived by integrating the pyroelectric current over the time. The resulting data have a good accuracy and quality which are helpful in detecting weak ferroelectric phase transitions induced by pulsed fields with a fast field sweep rate. In this paper, we introduce this measurement system in detail including the method, principle and its advantages in comparison with those in static fields. Recent study and progress of magnetoelectric multiferroic materials under high magnetic fields are also reported.