Tetragonal Superstructure of the Antiskyrmion Hosting Heusler Compound Mn_1.4PtSn

Abstract

Skyrmions in non-centrosymmetric magnets are vortex-like spin arrangements, viewed as potential candidates for information storage devices. The crystal structure and noncollinear magnetic structure together with magnetic and spin-orbit interactions define the symmetry of the skyrmion structure. We outline the importance of these parameters in the Heusler compound Mn_1.4PtSn which hosts antiskyrmions, a vortex-like spin texture related to skyrmions. We overcome the challenge of growing large micro-twin-free single crystals of Mn_1.4PtSn, which has proved to be the bottleneck for realizing bulk skyrmionic/antiskyrmionic states in a compound. The use of 5d-transition metal, platinum, together with manganese as constituents in the Heusler compound such as Mn_1.4PtSn is a precondition for the noncollinear magnetic structure. Because of the tetragonal inverse Heusler structure, Mn_1.4PtSn exhibits large magneto-crystalline anisotropy and <i>D</i> _<i>2d</i> symmetry, which are necessary for antiskyrmions. The superstructure in Mn_1.4PtSn is induced by Mn-vacancies, which enable a ferromagnetic exchange interaction to occur. Mn_1.4PtSn, the first known tetragonal Heusler superstructure compound, opens up a new research direction for properties related to the superstructure in a family containing thousands of compounds.