Investigation of hyperfine interactions in RMO 3 (R = La, Nd; M = Cr, Fe) antiferromagnetic perovskite oxides using PAC spectroscopy

Abstract

The local magnetic interaction at the transition metal sites in RMO 3 (R = La, Nd; M = Cr, Fe) compounds has been investigated by perturbed angular correlation (PAC) technique using 181 Hf→ 181 Ta probe nuclei. The present measurements cover a temperature range from 10 K to 1000 K. Above the respective Néel temperature, each compound shows a unique quadrupolar frequency that decreases linearly with temperature. These interactions were assigned to the radioactive probe substituting Cr or Fe sites. Below T N , a combined electric plus magnetic hyperfine interaction was observed. The magnetic interaction revealed that the super transferred hyperfine fields on 181 Ta at the Cr sites in (La,Nd)CrO 3 extrapolated to 0 K, are much smaller than the corresponding values at Fe sites in (La,Nd)FeO 3 . This difference was attributed to different distribution of d electrons in Cr 3+ (3d 3 ) and Fe 3+ (3d 5 ) ions in each compound. As the fields for Nd compounds are smaller than those for La compounds, the role of rare-earth ions in the magnetism of these oxides is also discussed.

Local inhomogeneous state in multiferroic SmCrO3

“…Finally, the fits below T N Cr have been perfectly performed without the inclusion of typical combined interactions (electric field gradient and magnetic hyperfine field interactions, EFG+MHF). In fact, the PAC studies in the RCrO 3 show that down to the ordering temperature of R, there is not an observable MHF 50,51,53,56 . Only the R(t) spectrum at T = 16 K, i.e.…”

Investigation of hyperfine interactions in GdCrO3 perovskite oxide using PAC spectroscopy

“…The observed B hf (0) values for GdCrO 3 and NdCrO 3 perovskites measured with 181 Ta are quite similar but they are much smaller than the corresponding value for LaCrO 3 where La +3 has no 4f-electrons [5,6]. The reason for this difference may be understood by considering the local magnetic moments of Cr and rare earth ions both of which contribute to hyperfine fields in these compounds.…”

“…Included in this table are also de data for LaCrO 3 and NdCrO 3 [6] for the purpose of comparison. These interactions were attributed to 181 Ta probe nuclei occupying Cr sites.…”

“…2. Solid lines in this figure are the Brillouin functions for Similar results for NdCrO 3 and LaCrO 3 taken from reference [6] have been included in this table for the purpose of comparison the spin J = 3/2 of Cr +3 fitted to experimental data. The value of the field B hf (0) extrapolated to 0 K is 1.1(1) T, which is quite similar to that observed for NdCrO 3 (see Table 1).…”

“…However, no microscopic study has been reported. It would therefore be interesting to study GdCrO 3 with some microscopic technique and compare the magnetic interactions in this compound, in which the rare-earth metal ion has seven 4f-electrons, with NdCrO 3 and LaCrO 3 in which there are three and zero 4f-electrons respectively [5,6]. The present study reports the results of PAC measurements in GdCrO 3 using 111 In ( 111 Cd) and 181 Hf( 181 Ta) probe nuclei to obtain the temperature dependence of magnetic hyperfine field (mhf) at Cr sites.…”