A Review of the Low Temperature Properties of the Rare Earth Vanadates

Abstract

The rare earth vanadates have long been studied for their interesting magnetic properties and cooperative Jahn–Teller distortions. In the main, most of this work has been carried out at temperatures down to 1 K or so (e.g. Gehring and Gehring 1975). In this review NMRON, and other low temperature experiments in the mK regime, are presented and discussed. It will be argued that the low temperature properties of these compounds are just as interesting as their high temperature counterparts. In general, the nuclear and electronic wavefunctions become intermixed, leading to a variety of interesting physical effects, such as enhanced nuclear magnetism, quadrupolar induced intermediate state re-orientation etc. These effects have, in turn, spawned new methods for the investigation of magnetic structures, and thermometric detection of NMR both by internal and external thermometers. Several experiments are suggested, including magnetic refrigeration, Mössbauer, EPR in the ≈30 GHz range, in addition to thermometric NMR and NMRON.

Influence of the Cr5+ ion on the magnetic properties of YbCrO4 oxide

“…Such doublet can be described by an effective spin S= 1 2 and a spectroscopic g-tensor which, in the case of axial symmetry, has two components g z and g > defined by 4 : g z ¼ 6:08 and g > =0.85 [4]. Surprisingly, in the magnetically ordered state, the Yb moments do not lie along the easy c-axis but in the a-b plane, which constitutes a hard magnetic plane.…”

“…For a polycrystalline sample, the saturated magnetisation of an extremely anisotropic doublet (i.e. g > /g z 51) averaged over all orientations is ence in the magnetic ordering temperature between the isostructural YbCrO 4 (T C =25 K) and YbVO 4 (T N =93 mK) oxides, coupled with a different sign of the magnetic interactions and the alignment of the Yb 3+ magnetic moments along the a-b plane in the YbCrO 4 oxide, points to the dominant role that the Cr 5+ magnetic ion plays in determining the overall magnetic ordering temperature, as well as polarising the magnetic moments of the Yb 3+ ions along a hard direction of magnetisation.…”

“…Rare earth chromates constitute a subgroup of the family of compounds of general formula RXO 4 , where R(III)=rare earth, while X(V) symbolises the following ions: V(V), As(V), P(V) and Cr(V) [1]. Few studies have been performed so far in the mentioned chromates [2].…”

“…Few studies have been performed so far in the mentioned chromates [2]. We have focused on the magnetic properties of the zircon-type YbCrO 4 oxide. Basing on the existing studies on the isomorphic YbVO 4 , YbAsO 4 and YbPO 4 compounds, the influence of the Cr 5+ ion on the overall magnetic properties of the YbCrO 4 can be thoroughly assessed.…”

A comparative three-dimensional neutron depolarization study on RCrO4 oxides (R=Y, Er, Tm, Yb)

“…They crystallize into two different structural types: monazite (monoclinic symmetry, S. G. P2 1 /c) or zircon (tetragonal symmetry, S. G. I4 1 /amd), depending on the size of both the R(III) and the X(V) ions [1][2][3]. They have been subject to extensive studies concerning their optical and magnetic properties [4,5]. Rare earth chromates present two magnetic ions in the lattice, namely R(III) and Cr(V), so that they constitute an ideal tool to asses the nature of the magnetic 3d-4f interactions.…”