title: Geometrical Spin Frustration of Unusually High Valence Fe(5+) in the Double Perovskite La2LiFeO6.
abstract: A double perovskite-structure oxide La2LiFeO6 with unusually high-valence Fe(5+) was synthesized using a high-pressure technique. The Li(+) and Fe(5+) ions at the B site in the rhombohedral R3̅ perovskite structure are ordered in a rock salt manner, and the resultant tetrahedral network of Fe(5+) gives geometrical spin frustration, which is consistent with a large frustration index f (|θ|/TN) ≈ 10. Mg(2+) substitution for Li(+) produces Fe(4+) from some Fe(5+) and changes the magnetic properties. The Weiss temperature is increased from -119 to 21 K by the substitution of only 1%, significantly decreasing the frustration index. The geometrical frustration of the Fe(5+) spin sublattice cannot be tolerant for even a very small amount of Fe(4+) disturbance.
authors.affiliation: Institute for Chemical Research, Kyoto University , Uji, Kyoto 611-0011, Japan.
authors.forename: Peng
authors.initials: P
authors.lastname: Xiong
authors.affiliation: Institute for Chemical Research, Kyoto University , Uji, Kyoto 611-0011, Japan.
authors.forename: Hayato
authors.initials: H
authors.lastname: Seki
authors.affiliation: Institute for Chemical Research, Kyoto University , Uji, Kyoto 611-0011, Japan.
authors.forename: Haichuan
authors.initials: H
authors.lastname: Guo
authors.affiliation: Institute for Chemical Research, Kyoto University , Uji, Kyoto 611-0011, Japan.
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Hosaka
authors.affiliation: Institute for Chemical Research, Kyoto University , Uji, Kyoto 611-0011, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Saito
authors.affiliation: Japan Synchrotron Radiation Research Institute , SPring-8, Hyogo 679-5198, Japan.
authors.forename: Masaichiro
authors.initials: M
authors.lastname: Mizumaki
authors.affiliation: Institute for Chemical Research, Kyoto University , Uji, Kyoto 611-0011, Japan.|Japan Science and Technology Agency, CREST , Uji, Kyoto 611-0011, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Shimakawa