EAPSI: Pressure and Magnetic Field Effects on Certain Magnetic Crystals

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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.