Magnetic Anisotropy of Lu₂Co_17-xSi_xSingle Crystals

Abstract

Magnetic anisotropy of Lu 2 Co 17−x Si x single crystals grown by the Czochralski method was investigated. The homogeneity range of Si substitution for Co extends up to x = 3.4 in Lu2Co17−xSix solid solutions. The unit cell volume, Curie temperature, and spontaneous magnetic moment decrease monotonously with increasing Si content. Lu2Co17 has the easyplane type of magnetic anisotropy in the ground state, which changes into the easy-axis type by two spin-reorientation transitions of the second-order, the easy-plane-easy-cone at T SR1 ∼ 680 K and the easy-cone -easy-axis at TSR2 ∼ 730 K. Upon Si substitution, the observed spin-reorientations shift towards the lower temperatures for Lu 2 Co 17−x Si x (T SR1 ∼ 75 K and TSR2 ∼ 130 K in Lu2Co16Si) and vanish for compounds with 1 < x ≤ 3.4, which have the uniaxial type of magnetic anisotropy in the whole temperature range of magnetic order. ) and Gd 3+ (Gd does not contribute to anisotropy) give information on the Co sublattice anisotropy and its changes upon partial substitution by a third M element. Previous investigations with Si were carried out on polycrystalline samples; however, single crystals are strongly desirable for the magnetic anisotropy investigations. The presence of the spontaneous spin-reorientation transitions (SRT) from the easy-plane to the easy-axis was reported in [4,6,7] along with the change of the MA type upon Si substitution for compounds with Y and Gd, whereas Ce 2 Co 17−x Si x compounds were found to be uniaxial for all Si content. There are some works dedicated to the study of magnetic anisotropy of Lu 2 Co 17 single