Magnetotransport, spin reorientation, and anomalous ferrimagnetic-to-antiferromagnetic phase transition in epitaxial Mn2Sb alloy thin films

• Published in: Acta materialia 2023-10, Vol.259, p.119257, Article 119257
• Main Authors: Chen, Ting-Wei, Liu, Shiqi, Zhang, Ying, Tang, Fang, Ying, Jing-Shi, Li, Shuang-Shuang, Chen, Lei, Luo, Fu-Sheng, Zhang, Shu-Juan, Fang, Yong, Ke, Shanming, Zhao, Weiyao, Zheng, Ren-Kui
• Format: Article
• Language: English
• Subjects: Anomalous Hall effect; Antiferromagnetic phase; Magnetoresistance; Mn2Sb film; Molecular beam epitaxy
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/j.actamat.2023.119257

High-quality ferrimagnetic Mn2Sb epitaxial thin films have been successfully grown on SrTiO3 (001) single-crystal substrates via systematically optimizing the growth parameters using molecular beam epitaxy. Magnetotransport and magnetic measurements reveal that a spin reorientation transition occurs in the 260–150 K region where the direction of spins rotates from out-of-plane to in-plane upon cooling, resulting in the ferrimagnetic(II) phase, followed by a giant magnetoresistance associated anomalous ferrimagnetic(II)-to-canted antiferromagnetic (c-AFM) phase transition in the 150–115 K region, resulting in the c-AFM ground state, both of which are completely absent and have yet not been previously observed in Mn2Sb bulk and thin films. Temperature-dependent X-ray diffraction measurements reveal that the low-temperature c-AFM phase originates from the contraction of the out-of-plane lattice constant c, which would increase the exchange interaction between neighbouring magnetic sublattices and thus stabilize the c-AFM phase. DFT calculations reveal that substrate clamping is the cause of the unique c-axis contraction in Mn2Sb films. For the 24-nm films, there is almost no out-of-plane magnetization in the ground state, but exists a weak in-plane remanent magnetization (∼0.4 μB/f.u.) and anomalous Hall effects, implying spin canting within the ab plane. With decreasing film thickness from 64 to 8 nm, the out-of-plane saturation magnetization at 10 K increases by approximately 10 times, and for the 8-nm film, its saturation magnetization (4.8 μB/f.u.) is 2.8 times larger than that of Mn2Sb bulk (∼1.74 μB/f.u.), both of which are attributed to the interfacial strain effect. Our work demonstrates that Mn2Sb films grown on perovskite oxide substrates show anomalous spin-charge-lattice coupling phenomena, which may inspire more study of its basic properties and potential device applications. [Display omitted]