High-field magnetization and magnetic structure of Tb₃Co

Abstract

The measurements of the magnetization in high steady and pulsed fields together with neutron diffraction measurements on a powder sample and on a single crystal have been performed to study the magnetic state of the Tb₃Co compound. It has been shown that the modulated antiferromagnetic structure which exists in Tb₃Co below <em>T</em>_N = 82 K transforms to the incommensurate magnetic structure with a strong ferromagnetic component along the <em>c</em>-axis with further cooling below the critical temperature <em>T</em>_t ≈ 72 K. The phase transition from the high-temperature to the low-temperature magnetic state at <em>T</em>_t is of first order. The incommensurability of the low-temperature magnetic structure of Tb₃Co is attributed to the non-Kramers character of the Tb³⁺ ion in combination with competition between the indirect exchange interaction and the low-symmetry crystal electric field.