Investigation of the Spin-Phase Separation in LaCoO3 by High-field Magnetization

2014 Fiscal Year Final Research Report

• Project/Area Number: 24540365
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Condensed matter physics II
• Research Institution: The University of Electro-Communications
• Principal Investigator: ASAI Kichizo 電気通信大学, 情報理工学(系)研究科, 教授 (00109795)
• Co-Investigator(Kenkyū-buntansha): SATO Keisuke 茨城工業高等専門学校, その他部局等, 講師 (10418212) ; KOBAYASHI Yoshihiko 東京医科大学, 医学部, 講師 (60293122) ; NAKAMURA Jin 電気通信大学, 情報理工学(系)研究科, 准教授 (50313416)
• Co-Investigator(Renkei-kenkyūsha): KINDO Koichi 東京大学, 物性研究所, 教授 (20205058)
• Project Period (FY): 2012-04-01 – 2015-03-31
• Keywords: スピン転移 / スピン相分離 / Co酸化物 / 強磁場磁化過程 / 強磁場磁歪 / 強磁場物性 / 強相関電子系 / ペロブスカイト

Outline of Final Research Achievements

The present study reveals the mechanism of the temperature-induced spin-state transition of LaCoO3 by investigating the high-field magnetization process of the doped LaCoO3 specimens. The Co3+ ions, which are in the low-spin (LS) state in the lowest temperature, are thermally excited to the high-spin (HS) state above about 30 K. However, the number of the Co3+ ions in the HS state is limited to about 15 % due to a large repulsive interaction among HS Co3+ ions. With further increase of the temperature, the remaining LS Co3+ ions are thermally excited to the intermediate-spin (IS) state around 100 K. It is suggested that other physical properties, such as magnetostriction, of LaCoO3 can be understood in accordance with the present model where HS and IS states coexist above 100 K.

Free Research Field

物性物理（磁性）