Recently, Associate Researcher HAN Yuyan from the High Magnetic Field Laboratory, the Hefei Institutes of Physical Science of the Chinese Academy of Sciences, collaborated with Associate Professor KAN Xucai and Associate Professor GAO Wenshuai from Anhui University successfully revealed the relationship between the magnetic structure and physical properties of EuAgSb single crystals, including their anomalous and topological Hall effects, contributing to the understanding of magnetic topological materials.
These findings were published online in the Journal of Alloys and Compounds.
Magnetic topological materials show great potential applications in devices such as magnetic switches and magnetic storage. Thus, it is imperative to synthesize new magnetic topological materials and explore their physical characteristics.
In this study, researchers investigated the physical properties of EuAgSb single crystals, a type of Eu-based compound that displayed unique magnetic and electronic behaviors. The EuAgSb material contained Sb atoms that supported quasi-two-dimensional Dirac fermions, and its magnetic properties could be controlled by adjusting temperature and magnetic field, which also changed its electronic structure. The team grew EuAgSb crystals using the flux method and conducted a detailed study of its magnetic, thermal, and electrical properties. They discovered that the material undergoes an antiferromagnetic transition at low temperatures, which can be suppressed with a stronger magnetic field. This transition was linked to an increase in magnetic entropy, as confirmed by heat capacity measurements.
Resistivity tests showed that EuAgSb behaves as a metal, with its resistivity increasing due to thermal fluctuations of the Eu magnetic moments around the transition temperature. As the temperature droped further, resistivity decreased because the Eu moments form a long-range order. The team also studied the Hall effect and found significant anomalous Hall effect (AHE) and topological Hall effect (THE) below the transition temperature, both of which disappeared when the temperature rose above it. These effects highlighted the connection between the material's magnetic structure and its electrical properties.
The research demonstrated how changes in temperature and magnetic field can alter the magnetic structure of EuAgSb, affecting its magnetic, thermal, and electrical properties.
These findings enhanced the understanding of magnetic topological materials establishing an experimental foundation for the development of devices based on such materials, according to the team.
Results of Hall effect, anomalous Hall effect and topological Hall effect. (Image by HAN Yuyan)