Spin-state transition and phase separation in a multiorbital Hubbard model

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Ryo Suzuki,¹ Tsutomu Watanabe,² and Sumio Ishihara¹
¹Department of Physics, Tohoku University, Sendai 980-8578, Japan
²Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan

Received 9 May 2009; revised 26 June 2009; published 18 August 2009

Westudy the spin-state transition and the phase separation involved inthis transition based on the multiorbital Hubbard model. Multiple spinstates are realized by changing the energy separation between twoorbitals and the on-site Hund coupling. By utilizing the variationalMonte-Carlo simulation, we analyze the electronic and magnetic structures inhole doped and undoped states. Electronic phase separation occurs betweenthe low-spin band insulating state and the high-spin ferromagnetic metallicstate. The difference in the band widths of the twoorbitals is of prime importance for the spin-state transition andthe phase separation.

URL:	http://link.aps.org/doi/10.1103/PhysRevB.80.054410
DOI:	10.1103/PhysRevB.80.054410
PACS:	75.25.+z; 71.70.-d; 71.30.+h 75.25.+z Spin arrangements in magnetically ordered materials 71.70.-d Level splitting and interactions (condensed matter) 71.30.+h Metal-insulator transitions and other electronic transitions YEAR: 2009
KEYWORDS:	electronic structure, ferromagnetic materials, Hubbard model, magnetic structure, Monte Carlo methods, phase separation, spin waves

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