A research team led by HAN Yuyan from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences, in collaboration with Prof. LIU Xiansong's group from Anhui University, conducted a systematic investigation of the physical properties of semiconductor-type EuMnSb₂ single crystals.

Their findings, published in Journal of Alloys and Compounds, contribute to the growing interest in magnetic topological materials.

As science progresses, magnetic topological materials have emerged as promising candidates for applications in areas such as magnetic switches and magnetic storage devices. Therefore, it is particularly important to synthesize novel magnetic topological materials and explore their physical properties.

In this study, the researchers synthesized the EuMnSb₂ single crystals by the flux method and investigated its magnetic, magnetoresistance, and specific heat properties.

They found that when stibium (Sb) was used as a flux, the crystals exhibited metallic electrical transport property, while when stannum (Sn) was used, the crystals exhibited semiconductor-type transport property. The EuMnSb₂ crystal demonstrated two magnetic transitions, corresponding to the paramagnetic-antiferromagnetic transition and the reorientation of Eu moments.

In addition, the magnetic field can modulate the magnetic, magnetoresistance, and specific heat properties. In particular, under strong magnetic fields, the material exhibits anisotropic magnetoresistance and giant negative magnetoresistance.

Based on these experimental results, the researchers constructed the electronic phase diagram of this material, which is classified into antiferromagnetic semiconductor, paramagnetic semiconductor, and paramagnetic metal. The aforementioned unique properties of the EuMnSb₂ can be attributed to the fact that both magnetic field and temperature affect the orientation of Eu moments, thereby inducing changes in magnetic entropy and band structure.

"Our findings elucidate the correlation between magnetic moments and physical properties in magnetic topological materials, thus providing experimental avenues for their potential application in electronic devices," said HAN Yuyan.

H-T phase diagrams for H//a (a) and H//bc (b) are extracted from the magnetic susceptibility, specific heat capacity, and resistivity measurements. (Image by HAN Yuyan)