Magnetic anisotropy of single-crystalline Mn3Sn in triangular and helix-phase states

The magnetic structure and phase transitions in single-crystalline Mn3Sn with the D019 structure have been investigated by torque measurements and magnetic measurements. The results show that a triangular antiferromagnet (AFM) and a weak ferromagnet coexist above 270 K. At these temperatures, the torque measurements indicate a six-fold symmetry and another two-fold symmetry of the magnetic anisotropy. The [112¯0] direction is the lowest-energy state in the triangular configuration. At low temperatures, two AFM helix-phase states are found in an applied magnetic field (H): In one of them, the [112¯0] direction is the easiest deviation direction from the AFM state. In the other, it is the [0001] direction. The variation of the two states with temperature (T) and magnetic field is presented in an H-T phase diagram.