Hyperfine interaction measurements in LaCrO{sub 3} and LaFeO{sub 3} perovskites using perturbed angular correlation spectroscopy
The perturbed angular correlation (PAC) technique was used to study the hyperfine interactions in the antiferromagnetic and paramagnetic regions of the distorted perovskites LaCrO{sub 3} and LaFeO{sub 3}. The dilute {sup 111}In{r_arrow}{sup 111}Cd nuclear probes were introduced into the samples through a chemical process. The present measurements cover the temperature ranges from 15 to 848 K for LaCrO{sub 3} and 77 to 1324 K for LaFeO{sub 3}. Two distinct electric-quadrupole interactions were observed in each compound. The lower quadrupole frequency was assigned to the transition-metal atom site while the higher frequency was attributed to the lanthanum site in both cases. Temperature dependence of the electric-quadrupole interaction parameters indicated structural phase transitions at around 512 and 1223 K, respectively, in LaCrO{sub 3} and LaFeO{sub 3}. The phase transitions were associated with the change from an orthorhombic to rhombohedral structure and characterized by a sudden increase in the electric field gradient V{sub zz} and a decrease in the asymmetry parameter {eta} for both sites. PAC spectra measured below the Ne{prime}el temperature revealed that at 0 K the supertransferred magnetic hyperfine field on {sup 111}Cd at the Cr site in LaCrO{sub 3} (2.4 T) is much smaller than at the Fe site in LaFeO{sub 3} (19.4 T). The magnetic field on {sup 111}Cd at La sites in both compounds is of the order of 0.3 T. Additional measurements were made to determine the magnetic hyperfine field using the probe nucleus {sup 140}La{r_arrow}{sup 140}Ce. The result reconfirmed that a relatively weak hyperfine field is supertransferred to the probe atoms at La sites.
- Sponsoring Organization:
- (US)
- OSTI ID:
- 40203462
- Journal Information:
- Physical Review B, Vol. 63, Issue 22; Other Information: DOI: 10.1103/PhysRevB.63.224104; Othernumber: PRBMDO000063000022224104000001; 030122PRB; PBD: 1 Jun 2001; ISSN 0163-1829
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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