Experimental and theoretical investigation of magnetism in single crystalline Mn₂FeSn

Heusler compounds with hexagonal and tetragonal crystal structures are of great interest because they are potential candidates for exhibiting high magnetocrystalline anisotropy, non-collinear magnetic structures, and topological magnetic phases [1,2]. We have grown single crystals of one such compound, Mn₂FeSn, in hexagonal structure using the flux method. X-ray diffraction (XRD) analysis indicates that the crystals are oriented with the basal plane (001) parallel to the sample surface. The elemental composition determined by energy-dispersive X-ray spectroscopy (EDX) is Mn_2.09Fe_0.91Sn_1.0. Magnetization measurements as a function of temperature, with the magnetic field applied perpendicular to the c-axis (along the sample surface), reveal a complex spin structure with two magnetic transitions at 220 K and 283 K. The first corresponds to spin reorientation transition and the second is the Curite temperature. The saturation magnetization measured at 60 K is about 4 μ_B/f.u which is roughly half of the value (7.8 μ_B/f.u) obtained from density functional calculations assuming a ferromagnetic ground state. This discrepancy suggests that the ground state of Mn₂FeSn may consist of a mixture of ferromagnetic and antiferromagnetic or non-collinear spin ordering. Details of the magnetic structure obtained from both theoretical calculations and magnetic measurements will be presented.

1. A. Nayak et. al, Magnetic antiskyrmions above room temperature in tetragonal Heusler materials, Nature 548, 561 (2017).

2. J. Herren et. al, Structural and magnetic properties of bulk Mn2PtSn, J. Phys.: Condens. Matter 30, 475801 (2018).