Browsing by Author "Mo, S.K."

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    Mott localization in a pure stripe antiferromagnet ${\mathrm{Rb}}_{1\ensuremath{-}\ensuremath{\delta}}{\mathrm{Fe}}_{1.5\ensuremath{-}\ensuremath{\sigma}}{\mathrm{S}}_{2}$
    (American Physical Society, 2015) 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.
    A combination of neutron diffraction and angle-resolved photoemission spectroscopy measurements on a pure antiferromagnetic stripe Rb1−δFe1.5−σS2 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 √5×√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.
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    Mott localization in a pure stripe antiferromagnet Rb1−δFe1.5−σS2
    (American Physical Society, 2015) 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.
    A combination of neutron diffraction and angle-resolved photoemission spectroscopy measurements on a pure antiferromagnetic stripe Rb1−δFe1.5−σS2 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 5√×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.