Compositional Dependence of X-Ray Absorption Spectra on Magnetic Circular Dichroism and Near-Edge Structure at Co K Edge in La 1-x Sr x CoO 3 (0≤x≤0.6)

• Published in: Japanese Journal of Applied Physics Vol. 43; no. 7R; p. 4171
• Main Authors: Hanashima, Takayasu, Azuhata, Satoshi, Yamawaki, Kouji, Shimizu, Norio, Mori, Takeharu, Tanaka, Masahiko, Sasaki, Satoshi
• Format: Journal Article
• Language: English
• Published: 01.07.2004
• ISSN: 0021-4922; 1347-4065
• DOI: 10.1143/JJAP.43.4171

We have studied the effect of Sr doping on the magnetic structure of La 1- x Sr x CoO 3 ( x =0, 0.2, 0.3, 0.4, 0.5 and 0.6) by X-ray magnetic circular dichroism (XMCD) at Co K absorption edges. A negative XMCD peak was clearly observed for pure LaCoO 3 at E =7.719 keV within the threshold region of the main edge, suggesting the existence of the intermediate-spin state of Co 3+ . A positive XMCD peak appeared at E =7.723 keV by Sr substitution of La in LaCoO 3 ( x ≥0.2) in accordance with the low-spin state of Co 4+ and X-ray absorption near-edge-structure (XANES) spectra. A negative XMCD peak was also observed at the pre-edge, which can be explained as the hybridization with the neighboring Co 4+ in the dipole transition. The dispersion-type XMCD signals at the main edge may be rationalized with the hypothetical double-exchange interaction between Co 3+ and Co 4+ .