title: Magnetic and electronic properties of La3MO7and possible polaron formation in hole-doped La3MO7(M  =  Ru and Os).
abstract: Oxides with 4d/5d transition metal ions are physically interesting for their particular crystalline structures as well as the spin-orbit coupled electronic structures. Recent experiments revealed a series of 4d/5d transition metal oxides R3MO7(R: rare earth; M: 4d/5d transition metal) with unique quasi-one-dimensional M chains. Here first-principles calculations have been performed to study the electronic structures of La3OsO7and La3RuO7. Our study confirm both of them to be Mott insulating antiferromagnets with identical magnetic order. The reduced magnetic moments, which are much smaller than the expected value for ideal high-spin state (3 t2gorbitals occupied), are attributed to the strong p  -  d hybridization with oxygen ions, instead of the spin-orbit coupling. The Ca-doping to La3OsO7and La3RuO7can not only modulate the nominal carrier density but also affect the orbital order as well as the local distortions. The Coulombic attraction and particular orbital order would prefer to form polarons, which might explain the puzzling insulating behavior of doped 5d transition metal oxides. In addition, our calculations predict that the Ca-doping can trigger ferromagnetism in La3RuO7but not in La3OsO7.
authors.affiliation: Department of Physics, Southeast University, Nanjing 211189, People's Republic of China.
authors.forename: Bin
authors.initials: B
authors.lastname: Gao
authors.forename: Yakui
authors.initials: Y
authors.lastname: Weng
authors.forename: Jun-Jie
authors.initials: JJ
authors.lastname: Zhang
authors.forename: Huimin
authors.initials: H
authors.lastname: Zhang
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Shuai
authors.initials: S
authors.lastname: Dong