Magnetic structures in the magnetic phase diagram ofHo2RhIn8

Abstract

The magnetic phase diagram of the tetragonal ${\mathrm{Ho}}_{2}{\mathrm{RhIn}}_{8}$ compound has similar features to many related systems, revealing a zero magnetic field AF1 and a field-induced AF2 phases. Details of the magnetic order in the AF2 phase were not reported yet for any of the related compounds. In addition, only the ${\mathrm{Ho}}_{2}{\mathrm{RhIn}}_{8}$ phase diagram contains a small region of the incommensurate zero-field AF3 phase. We have performed a number of neutron diffraction experiments on single crystals of ${\mathrm{Ho}}_{2}{\mathrm{RhIn}}_{8}$ using several diffractometers including experiments in both horizontal and vertical magnetic fields up to 4 T. We present details of the magnetic structures in all magnetic phases of the rich phase diagram of ${\mathrm{Ho}}_{2}{\mathrm{RhIn}}_{8}$. The Ho magnetic moments point along the tetragonal $c$ axis in every phase. The ground-state AF1 phase is characterized by propagation vector $\mathbf{k}=(1/2,0,0)$. The more complex ferrimagnetic AF2 phase is described by four propagation vectors ${\mathbf{k}}_{0}=(0,0,0),{\mathbf{k}}_{1}=(1/2,0,0),{\mathbf{k}}_{2}=(0,1/2,1/2),{\mathbf{k}}_{3}=(1/2,1/2,1/2)$. The magnetic structure in the AF3 phase is incommensurate with ${\mathbf{k}}_{AF3}=(0.5,\ensuremath{\delta},0)$. Our results are consistent with theoretical calculations based on crystal field theory.