Magnetic and magnetoelastic properties of antiferromagnet FeGe2

Abstract

The magnetic susceptibility χ of single-crystal antiferromagnet FeGe2 (TN = 289 K) was measured in the temperature range from 4.2 to 300 K in a magnetic field H up to 40 kOe applied along the main crystallographic axes. For the antiferromagnetic (AFM) state at low temperatures, a strong increase in χ is observed with increasing H applied along the [100] axis, which reaches saturation at H≥H0∼ 11 kOe. It is assumed that this behavior is associated with a field-induced change in the AFM domain structure, and the single-domain state is realized in a field above H0 with the AFM axis perpendicular to the field direction. The study of χ under the uniaxial Pa and uniform P pressures in a wide temperature range has revealed an anomalously large increase in χ in AFM state with increasing uniaxial pressure for Pa||H||[100] at H≪H0. The observed growth of χ saturates at pressure Pa≥Pa∗≃1.5 kbar and suggests the formation of the single-domain state for the above conditions. The values of uniform pressure effect on χ was found to lie in the range dln⁡χ/dP = − (2–3) Mbar–1, being weakly dependent on the magnetic state and field direction. In addition, the uniform pressure effect on the transition temperature between two AFM structures in FeGe2, TM≃263 K, was found to be weak.