Magnetic order driven by orbital ordering in the semiconducting KFe1.5Se2

doi:10.1007/s11467-015-0527-4

Frontiers of Physics

2016, Vol. 11

Issue (2): 117401 https://doi.org/10.1007/s11467-015-0527-4

本期目录

Magnetic order driven by orbital ordering in the semiconducting KFe_1.5Se₂

Qing Jiang,Dao-Xin Yao(

)

1 State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275, China

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Abstract：

The two-orbital Hubbard model is studied numerically by using the Hartree-Fock approximation in both real space and momentum space, and the ground-state properties of the alkali metal iron selenide semiconducting KFe_1.5Se₂ are investigated. A rhombus-type Fe vacancy order with stripetype antiferromagnetic (AFM) order is found, as was observed in neutron scattering experiments [J. Zhao, et al., Phys. Rev. Lett. 109, 267003 (2012)]. Hopping parameters are obtained by fitting the experimentally observed stripe AFM phase in real space. These hopping parameters are then used to study the ground-state properties of the semiconductor in momentum space. It is found to be a strongly correlated system with a large on-site Coulomb repulsion U, similar to the AFM Mott insulator — the parent compound of copper oxide superconductors. We also find that the electronic occupation numbers and magnetizations in the d_xz and d_yz orbitals become different simultaneously when U>U_c (～3.4 eV), indicating orbital ordering. These results imply that the rotational symmetry between the two orbitals is broken by orbital ordering and thus drives the strong anisotropy of the magnetic coupling that has been observed by experiments and that the stripe-type AFM order in this compound may be caused by orbital ordering together with the observed large anisotropy.

Key words： iron-based superconductor two-orbital model stripe AFM phase rhombus Fe vacancy order orbital ordering

收稿日期: 2015-09-07 出版日期: 2016-04-29

Corresponding Author(s): Dao-Xin Yao

引用本文:

. [J]. Frontiers of Physics, 2016, 11(2): 117401.
Qing Jiang,Dao-Xin Yao. Magnetic order driven by orbital ordering in the semiconducting KFe_1.5Se₂. Front. Phys. , 2016, 11(2): 117401.

链接本文:

https://academic.hep.com.cn/fop/CN/10.1007/s11467-015-0527-4
https://academic.hep.com.cn/fop/CN/Y2016/V11/I2/117401

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