Single crystal growth and magnetic properties of La2−xMxCoO4 (M=Ca, Ba)

✍ Scribed by Kazumasa Horigane; Toru Uchida; Jun Akimitsu

• Publisher: Elsevier Science
• Year: 2006
• Tongue: English
• Weight: 208 KB
• Volume: 378-380
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2006.01.423

✦ Synopsis

Magnetic properties were investigated for single crystals of La 2Àx Ca x CoO 4 ð0:5pxp0:8Þ and for polycrystalline samples of La 2Àx Ba x CoO 4 ð0:5pxp0:9Þ. In the Ca system, the effective moment m eff decreased with increasing x from 4.0 m B ðx ¼ 0:5Þ to 3.0 m B ðx ¼ 0:720:8Þ, accompanied by a steep reduction of Weiss temperature Y. These drastic changes of the magnetic properties suggest a spin-state transition of the Co 3+ ions from the high-spin state to the intermediate-spin state. On the other hand, the effective moment of La 2Àx Ba x CoO 4 was almost 4.0 m B and there is no change of Weiss temperature Y. These facts suggest that the intermediate-spin state is related to the Co-O bond length, i.e. crystal fields.