Mott localization in a pure stripe antiferromagnet Rb1-delta Fe1.5-sigma S2

作者：Wang Meng; Yi Ming; Cao Huibo; de la Cruz C; Mo S K; Huang Q Z; Bourret Courchesne E; Dai Pengcheng; Lee D H; Shen Z X; Birgeneau R J

来源：Physical Review B, 2015, 92(12): 121101.

DOI：10.1103/PhysRevB.92.121101

A combination of neutron diffraction and angle-resolved photoemission spectroscopy measurements on a pure antiferromagnetic stripe Rb1-delta Fe1.5-sigma S2 is reported. A neutron diffraction experiment on a powder sample shows that a 98% volume fraction of the sample is in the antiferromagnetic stripe phase with rhombic iron vacancy order and a refined composition of Rb0.66Fe1.36S2, and that only 2% of the sample is in the block antiferromagnetic phase with root 5 x root 5 iron vacancy order. Furthermore, a neutron diffraction experiment on a single crystal shows that there is only a single phase with the stripe antiferromagnetic order with the refined composition of Rb0.78Fe1.35S2, while the phase with block antiferromagnetic order is absent. Angle-resolved photoemission spectroscopy measurements on the same crystal with the pure stripe phase reveal that the electronic structure is gapped at the Fermi level with a gap larger than 0.325 eV. The data collectively demonstrate that the extra 10% iron vacancies in addition to the rhombic iron vacancy order effectively impede the formation of the block antiferromagnetic phase; the data also suggest that the stripe antiferromagnetic phase with rhombic iron vacancy order is a Mott insulator.

• 出版日期2015-9-1