Field Induced Spin-State Transition in LaCoO3

• Published in: Journal of the Physical Society of Japan Vol. 78; no. 9
• Main Authors: SATO, Keisuke, MATSUO, Akira, KINDO, Koichi, KOBAYASHI, Yoshihiko, ASAI, Kichizo
• Format: Journal Article
• Language: English
• Published: Tokyo Physical Society of Japan 01-09-2009; The Physical Society of Japan
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Domain effects, magnetization curves, and hysteresis; Exact sciences and technology; Magnetic phase boundaries (including magnetic transitions, metamagnetism, etc.); Magnetic properties and materials; Magnetically ordered materials: other intrinsic properties; Magnetization curves, magnetization reversal, hysteresis, barkhausen and related effects; Physics; Level crossing; g-factor; LaCoO; Vacancies; Energy levels; Magnetization; Cobalt Lanthanum Oxides Mixed; High field; Magnetic field effects; high-field magnetization; spin-state transition; Magnetic transitions
• ISSN: 0031-9015; 1347-4073
• DOI: 10.1143/jpsj.78.093702

The magnetization of LaCoO3 shows a magnetic transition induced by level crossing at a magnetic field of 60 T below 25 K, which is consistent with the energy diagram determined from electron spin resonance experiments. However, the amount of Co ions with g=3.35 contributing to the magnetic transition is sample-dependent and at most 14% of the total Co ions in LaCoO3. We found that the rest of the Co ions also contribute to the magnetization, which is a maximum at around 100 K. We analyzed the magnetization assuming two kinds of Co species, CoI and CoII, both of which have the nonmagnetic ground state. The energies and the g values of the magnetic excited states are 135 K and 3.35 for CoI, and 250-260 K and 1.9-2.0 for CoII, respectively. CoI ions are suggested to be associated with oxygen vacancies and the surface of LaCoO3.