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arXiv · 2309.05945

Gap and magnetic engineering via doping and pressure in tuning the colossal magnetoresistance in (Mn$_{1-x}$Mg$_x$)$_3$Si$_2$Te$_6$

Chaoxin Huang·Mengwu Huo·Xing Huang·Hui Liu·Lisi Li·Ziyou Zhang·Zhiqiang Chen·Yifeng Han·Lan Chen·Feixiang Liang·Hongliang Dong·Bing Shen·Hualei Sun·Meng Wang
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Abstract

Ferrimagnetic nodal-line semiconductor Mn$_3$Si$_2$Te$_6$ keeps the records of colossal magnetoresistance (CMR) and angular magnetoresistance (AMR). Here we report tuning the electronic transport properties via doping and pressure in (Mn$_{1-x}$Mg$_x$)$_3$Si$_2$Te$_6$. As the substitution of nonmagnetic Mg$^{2+}$ for magnetic Mn$^{2+}$, ferrimagnetic transition temperature $T_C$ gradually decreases, while the resistivity increases significantly. At the same time, the CMR and AMR are both enhanced for the low-doping compositions (e.g., $x = 0.1$ and 0.2), which can be attributed to doping-induced broadening of the band gap and a larger variation range of the resistivity when undergoing a metal-insulator transition by applying a magnetic field along the $c$ axis. On the contrary, $T_C$ rises with increasing pressure due to the enhancement of the magnetic exchange interactions until a structural transition occurs at $\sim$13 GPa. Meanwhile, the activation gap is lowered under pressure and the magnetoresistance is decreased dramatically above 6 GPa where the gap is closed. At 20 and 26 GPa, evidences for a superconducting transition at $\sim$5 K are observed. The results reveal that doping and pressure are effective methods to tune the activation gap, and correspondingly, the CMR and AMR in nodal-line semiconductors, providing an approach to investigate the magnetoresistance materials for novel spintronic devices.

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Chaoxin Huang, Mengwu Huo, Xing Huang, Hui Liu, Lisi Li, Ziyou Zhang, Zhiqiang Chen, Yifeng Han, Lan Chen, Feixiang Liang, Hongliang Dong, Bing Shen, Hualei Sun, Meng Wang. 2023-09-12. Gap and magnetic engineering via doping and pressure in tuning the colossal magnetoresistance in (Mn$_{1-x}$Mg$_x$)$_3$Si$_2$Te$_6$. https://doi.org/10.1103/physrevb.109.205145

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