title: Theoretical studies of the dependence of EPR parameters on local structure for the tetragonal Er(3+) centres in YVO4 and ScVO4.
abstract: The dependences of the EPR parameters on the local distortion parameters Δθ and ΔR as well as the crystal-field parameters have been studied by diagonalizing the 364×364 complete energy matrices for a tetragonal Er(3+) centre in the YVO4 and ScVO4 crystals. The results show that the local distortion angle Δθ and the fourth-order crystal-field parameter Ā4 are most sensitive to the EPR g-factors g// and g⊥, whereas the local distortion length ΔR and the second-order parameter Ā2 are less sensitive to the g-factors. Furthermore, we found that the abnormal EPR g-factors for the Er(3+) ion in the ScVO4 may be ascribed to the stronger nephelauxetic effect and covalent bonding effect, as a result of an expanded local distortion for the Er(3+) centre in the ScVO4 crystal. Simultaneously, the contributions of the J-J mixing effects from the terms of excited states to the EPR parameters have been evaluated quantitatively.
authors.affiliation: Department of Physics, Xi'an University of Architecture and Technology, Xi'an 710055, China.
authors.forename: Rui-Peng
authors.initials: RP
authors.lastname: Chai
authors.affiliation: Xi'an University of Architecture and Technology Hua Qing College, Xi'an 710043, China.
authors.forename: Dan-Hui
authors.initials: DH
authors.lastname: Hao
authors.affiliation: Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China; International Centre for Materials Physics, Academia Sinica, Shenyang 110016, China. Electronic address: scu_xykuang@163.com.
authors.forename: Xiao-Yu
authors.initials: XY
authors.lastname: Kuang
authors.affiliation: Department of Physics, Xi'an University of Architecture and Technology, Xi'an 710055, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Liang
keywords: Covalent bonding effect; EPR parameters; J–J mixing effect; Local lattice structure