EAPSI: Pressure and Magnetic Field Effects on Certain Magnetic Crystals

有些材料的电性能会根据外部条件（如温度、磁场和压力）发生显著变化。这些材料可以用于改善电子功能和/或创造新的功能。一个这样的功能涉及利用电子的自旋性质，而不是像大多数电子那样利用它们的电荷性质。利用该功能的设备相对于其传统对应物提供了若干改进，包括但不限于功耗的降低和速度的提高。将被研究的磁性晶体表现出敏感地依赖于外部条件的特性，并且具有非常简单的晶体结构，这使其成为研究更复杂材料的理想模型系统。这项研究将与北京中国科学院的丛仁博士合作进行。Ren博士的实验室配备了进行所需电阻测量所需的设备：两个具有不同温度和磁场能力的低温系统以及一个适用于这些系统的高压单元。六硼化铕（EuB 6）是将被研究的晶体;最近的霍尔效应测量揭示了其宏观磁输运性质的相变。在顺磁相的霍尔电阻率表现出两个不同的线性区域与一个过渡点在一个单一的临界磁化在一个广泛的温度范围内，这被解释为渗透点的导电相。该项目的重点是通过在高压下对EuB 6进行磁输运测量来进一步了解这一现象。已知流体静压会大幅改变EuB 6的磁性状态;该项目旨在研究在环境压力下观察到的磁输运和磁化之间的密切相关性是否持续到高压。NSF EAPSI奖是与中国科技部合作资助的。

There are materials whose electrical properties change substantially depending on external conditions such as temperature, magnetic field, and pressure. These materials can potentially be used to improve electronic functionalities and/or create new ones. One such functionality involves the utilization of the spin property of electrons instead of their charge property like most electronics do. Devices which take advantage of this functionality offer several improvements over their traditional counterparts including, but not limited to, reduction in power consumption and increase in speed. The magnetic crystal that will be studied exhibits properties that depend sensitively on the external conditions and has a very simple crystal structure which makes it an ideal model system for the study of more complex materials. This research will be conducted in collaboration with Dr. Cong Ren at the Chinese Academy of Sciences in Beijing. Dr. Ren's lab is equipped with the equipment needed to perform the desired resistance measurements: two cryogenic systems with different temperature and magnetic field capabilities as well as a high-pressure cell adaptable to these systems. Europium hexaboride (EuB6) is the crystal that will be studied; recent Hall Effect measurements revealed a percolative phase transition in its macroscopic magnetotransport property. The Hall resistivity in the paramagnetic phase exhibits two distinct linear regions with a transition point at a single critical magnetization over a broad temperature range, which was interpreted as the percolation point for the more conducting phase. This project focuses on the further understanding of this phenomenon by performing magnetotransport measurements on EuB6 under high pressure. Hydrostatic pressure is known to substantially modify the magnetic state of EuB6; this project aims to examine whether the close correlation between magnetotransport and magnetization observed in ambient pressure persists to high pressure. This NSF EAPSI award is funded in collaboration with the Chinese Ministry of Science and Technology.