Magnetization reversal in orthovanadateRVO3compounds (R=La, Nd, Sm, Gd, Er, and Y): Inhomogeneit

Abstract

Abstract:We report on a study of various RVO 3 single-crystal samples (R = La, Nd, Sm, Gd, Er and Y) which show temperature-induced magnetization reversal. For compounds with lighter rare-earths (R = La, Nd and Sm), magnetization reversal can be observed for magnetic field applied in the ab plane and along the c axis, whereas for the heavy rare-earths (R = Gd, Er) magnetization reversal is only observed when the field is applied along the a axis. YVO 3 has a magnetization reversal along all the main crystallographic axes in a modest applied field. We have found that some compounds are very sensitive to small trapped fields present in the superconducting solenoid of the magnetometer during the cooling. Based on the observed results, we argue that inhomogeniety caused by defects in the orbital sector in the quasi onedimensional orbital systems could account for the unusual magnetization reversal.

Study of phase coexistence in YVO3 and LaVO3

“…A single‐crystalline boule of 6 mm in diameter and 60–70 mm in length was then grown by the traveling solvent floating zone method. The crystallinity of the boule was checked by X‐ray analysis and the composition by the electron probe microanalysis …”

Critical phenomena and femtosecond ordering dynamics associated with electronic and spin-ordered phases inYVO3andGdVO3

“…The orientation of the V spins within the C-SO phase has not been reported for all members of the series and its dependence on the rare earth is still rather unclear. 18 Available evidence provided by magnetization and neutron-diffraction measurements suggests that the V spins lie in the bc plane for RVO 3 with small rare earths 17,19 and in the ab plane for larger rare earths 16,20 but it should be noted that the ab-plane configuration is forbidden by symmetry arguments. 16,17 These two regions of the magnetic RVO 3 phase diagram coincide approximately with those defined by the G-OO phase monoclinic angle.…”

X-ray diffraction study of the temperature-induced structural phase transitions in SmVO3

“…This phase separation is therefore possibly common to Tb, Gd, Eu, and Sm members of the RVO 3 series due to their similar, middle rare-earth radius. Furthermore, Tung et al 7 commented that the phase separation is consistent with, but not equivalent to, their model of MR based upon the existence of random field spins. However, in a neutron diffraction study, 14 no phase separation was observed in single-crystal TbVO 3 .…”

“…5 In this paper we focus on the R = Sm member of the series belonging to the third subgroup outlined above. In SmVO 3 , heat capacity measurements show T OO = 192.6 K and T N = 130 K. 7 The majority of RVO 3 compounds (excluding R = Pr, Ce, Lu) exhibit magnetization reversal (MR). Upon cooling SmVO 3 below T N , the magnetization, which is initially positive, smoothly reverses twice at T = 127.5 and 63.8 K. 7 A number of mechanisms for the MR have been proposed.…”

“…Upon cooling SmVO 3 below T N , the magnetization, which is initially positive, smoothly reverses twice at T = 127.5 and 63.8 K. 7 A number of mechanisms for the MR have been proposed. 7,10,11 Most recently Tung et al 7 explained that the MR occurs due to a minority of random field spins, forming a separate magnetic sublattice from the long-range, strongly coupled antiferromagnetic order. The random field spins are then believed to originate from defects in the orbital system.…”