TY - JOUR

T1 - Intermediate-spin state and properties

AU - Korotin, M.

AU - Ezhov, S. Yu

AU - Solovyev, I.

AU - Anisimov, V.

AU - Khomskii, D.

AU - Sawatzky, G.

PY - 1996

Y1 - 1996

N2 - The electronic structure of the perovskite (Formula presented) for different spin states of Co ions was calculated in the local-density approximation LDA+U approach. The ground state is found to be a nonmagnetic insulator with Co ions in a low-spin state. Somewhat higher in energy, we find two intermediate-spin states followed by a high-spin state at significantly higher energy. The calculations show that Co 3d states of (Formula presented) symmetry form narrow bands which could easily localize, while (Formula presented) orbitals, due to their strong hybridization with the oxygen 2p states, form a broad σ* band. With temperature variation which is simulated by a corresponding change of the lattice parameters, a transition from the low- to intermediate-spin state occurs. This intermediate-spin (occupation (Formula presented)(Formula presented)) can develop an orbital ordering which can account for the nonmetallic nature of (Formula presented) at 90 K<T<500 K. Possible explanations of the magnetic behavior and gradual insulator-metal transition are suggested.

AB - The electronic structure of the perovskite (Formula presented) for different spin states of Co ions was calculated in the local-density approximation LDA+U approach. The ground state is found to be a nonmagnetic insulator with Co ions in a low-spin state. Somewhat higher in energy, we find two intermediate-spin states followed by a high-spin state at significantly higher energy. The calculations show that Co 3d states of (Formula presented) symmetry form narrow bands which could easily localize, while (Formula presented) orbitals, due to their strong hybridization with the oxygen 2p states, form a broad σ* band. With temperature variation which is simulated by a corresponding change of the lattice parameters, a transition from the low- to intermediate-spin state occurs. This intermediate-spin (occupation (Formula presented)(Formula presented)) can develop an orbital ordering which can account for the nonmetallic nature of (Formula presented) at 90 K<T<500 K. Possible explanations of the magnetic behavior and gradual insulator-metal transition are suggested.

UR - http://www.scopus.com/inward/record.url?scp=0000144063&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.54.5309

DO - 10.1103/PhysRevB.54.5309

M3 - Article

AN - SCOPUS:0000144063

VL - 54

SP - 5309

EP - 5316

JO - Physical Review B - Condensed Matter and Materials Physics

JF - Physical Review B - Condensed Matter and Materials Physics

SN - 1098-0121

IS - 8

ER -