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arXiv · 2104.09127

Field-induced metal-to-insulator transition and colossal anisotropic magnetoresistance in a nearly Dirac material EuMnSb$_2$

Z. L. Sun·A. F. Wang·H. M. Mu·H. H. Wang·Z. F. Wang·T. Wu·Z. Y. Wang·X. Y. Zhou·X. H. Chen
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Abstract

How to realize applicably appreciated functionalities based on the coupling between charge and spin degrees of freedom is still a challenge in the field of spintronics. For example, anisotropic magnetoresistance (AMR) effect is utilized to read out the information stored by various magnetic structures, which usually originates from atomic spin-orbit coupling (SOC). However, the application of AMR in antiferromagnet-based spintronics is still hindered by rather small AMR value. Here, we discover a colossal AMR effect during the field-induced metal-to-insulator transition (MIT) in a nearly Dirac material EuMnSb$_2$ with an antiferromagnetic order of Eu$^{2+}$ moments. The colossal AMR reaches to an unprecedented value of 1.84$\times$10$^6$% at 2 K, which is four orders of magnitude larger than previously reported values in antiferromagnets. Based on density functional theory calculations, a Dirac-like band structure, which is strongly dependent on SOC, is confirmed around Y point and dominates the overall transport properties in the present sample with predominant electron-type carriers. Moreover, it is also revealed that the indirect band gap around Fermi level is dependent on the magnetic structure of Eu$^{2+}$ moments, which leads to the field-induced MIT and plays a key role on the colossal AMR effect. Finally, our present work suggests that the similar antiferromagnetic topological materials as EuMnSb$_2$, in which Dirac-like fermions is strongly modulated by SOC and antiferromagnetism, would be a fertile ground to explore applicably appreciated AMR effect.

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Z. L. Sun, A. F. Wang, H. M. Mu, H. H. Wang, Z. F. Wang, T. Wu, Z. Y. Wang, X. Y. Zhou, X. H. Chen. 2021-04-19. Field-induced metal-to-insulator transition and colossal anisotropic magnetoresistance in a nearly Dirac material EuMnSb$_2$. https://arxiv.org/abs/2104.09127

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