Inverse triangular spin structure and magnetic property of epitaxial D019-Mn3Sn and Mn3Ga thin films

Jay KOO

Geometrically frustrated antiferromagnets have been the subject of extensive theoretical and experimental works, mainly due to its disordered classical and quantum ground states whose short- or long-range order is determined by a delicate balance between (symmetric and antisymmetric) exchange interactions and magnetic anisotropy. In addition, large anomalous Hall and Nernst effects at room temperature have been evidenced from Mn3Sn[1] and Mn3Ge[2, 3]. The unexpected anomalous transport properties from these antiferromagnets are attributed to the inverse triangular spin structure in the basal plane. Moreover, the broken PT symmetry of the ground state spin structure allows the existence of gapless electronic excitations, i.e., the Weyl fermions, in the electronic band structure giving rise to large anomalous Hall and Nernst conductivities. These materials are currently of great interest to the topological magnetics community, due both to their fascinating Berry curvature driven magnetotransport properties and their potential applications in spintronic devices.
In this talk, magnetization properties associated with the inverse triangular AFM spin structure of Mn3Sn and Mn3Ga thin films will be presented. Neutron diffraction measurement of Mn3Sn and Mn3Ga thin films confirmed that the spin structure of our thin film is exactly the same type as the bulk specimen. Magnetic phase transition from the inverse triangular spin structure to the helical order was not detected. Transport property, mainly anomalous Hall effect, will also be discussed.

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[2] N. Kiyohara, T. Tomita, and S. Nakatsuji, Giant anomalous hall effect in the chiral antiferromagnet mn3ge, Physical Review Applied 5, 10.1103/physrevapplied.5.064009 (2016)
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