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arXiv · 2110.10911

Polaronic transport and thermoelectricity in Mn$_3$Si$_2$Te$_6$ single crystals

Yu Liu·Zhixiang Hu·Milinda Abeykoon·Eli Stavitski·Klaus Attenkofer·Eric D. Bauer·C. Petrovic
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Abstract

We carried out a comprehensive study of the structural, electrical transport, thermal and thermodynamic properties in ferrimagnetic Mn$_3$Si$_2$Te$_6$ single crystals. Mn and Te $K$-edge X-ray absorption spectroscopy and synchrotron powder X-ray diffraction were measured to provide information on the local atomic environment and the average crystal structure. The dc and ac magnetic susceptibility measurements indicate a second-order paramagnetic to ferrimagnetic transition at $T_c$ $\sim$ 74 K, which is further confirmed by the specific heat measurement. Mn$_3$Si$_2$Te$_6$ exhibits semiconducting behavior along with a large negative magnetoresistance of -87\% at $T_c$ and relatively high value of thermopower up to $\sim$ 10 mV/K at 5 K. Besides the rapidly increasing resistivity $\rho(T)$ and thermopower $S(T)$ below 20 K, the large discrepancy between activation energy for resistivity $E_\rho$ and thermopower $E_S$ above 20 K indicates the polaronic transport mechanism. Furthermore, the thermal conductivity $\kappa(T)$ of Mn$_3$Si$_2$Te$_6$ is notably rather low, comparable to Cr$_2$Si$_2$Te$_6$, and is strongly suppressed in magnetic field across $T_c$, indicating the presence of strong spin-lattice coupling, also similar with Cr$_2$Si$_2$Te$_6$.

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Yu Liu, Zhixiang Hu, Milinda Abeykoon, Eli Stavitski, Klaus Attenkofer, Eric D. Bauer, C. Petrovic. 2021-10-21. Polaronic transport and thermoelectricity in Mn$_3$Si$_2$Te$_6$ single crystals. https://doi.org/10.1103/physrevb.103.245122

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