A high-field magnetization study of a Nd2Fe14Si3 single crystal

Magnetization study of a single crystal of Nd2Fe14Si3 (with the rhombohedral Th2Zn17-type structure) reveals that the compound is a ferromagnet with a spontaneous magnetic moment of 32.3 mu(B) per formula unit (at T = 2 K) and a Curie temperature equal to 495 K. The easy-magnetization direction lies close to the b-axis, tilting slightly towards the c-axis. (The b-axis [120] is not a high-symmetry direction in the crystallographic class D-3d.) The observed strong magnetic anisotropy is attributed almost entirely to the Nd sublattice, as concluded from comparison with a Y2Fe14Si3 single crystal. A magnetic field applied along the c-axis induces a first-order spin reorientation transition at BFOMP = 20 T. In the process of magnetization the Nd and Fe sublattices behave as essentially non-collinear. This is manifest particularly in the downward curvature of the first (pre-FOMP) stage of the magnetization curve. It is proposed to regard this curvature as a validity criterion for the single-sublattice approximation.