Anisotropic magnetic properties of dysprosium iron garnet (DyIG)

Abstract

The magnetic properties of dysprosium iron garnet (DyIG) have been studied by performing high resolution powder neutron diffraction experiments and high dc fields magnetizations on single crystals. Among all the reflections (hkl) indexed in the nuclear cubic space group (CSG) Ia d with h+k+l=2n and k=[000], the superstructure lines (hkl)* forbidden by the symmetry (222)* and (622)* are not observed in the patterns at all temperatures. The pattern at 130 K is well interpreted within the magnetic modes F belonging to the irreducible representation (IR) T1g of the CSG and identified to the room temperature ferrimagnetic Néel model. The high magnetic field behavior of the spontaneous collinear magnetic structure (MS) along the easy axis (EA) <111> is isotropic. Below 130 K, the patterns exhibit additional magnetic superstructure lines. They are associated to the appearance of the spontaneous non collinear MS which is described in the subgroup of the CSG, R c within the IR A2g. A strong magnetization anisotropy (MA) is observed at 1.5 K in the low symmetry phases were the spin reorientation transition (SR) occur at TRS=14.5 K. The onset of MA is detected below two characteristic temperatures, Ta1=125 K and Ta 2=75 K respectively to the hard axis (HA) <100> and <110>. Symmetry arguments are used in the framework of the theory of representation analysis (RA) applied to the subgroup of R c, C2/c within the IR Ag. It seems that this MA results essentially from the difference between the spontaneous non collinear MS and the field induced (FI) configurations. All results are discussed with previous neutrons studies. © 2010 IOP Publishing Ltd.