A-Type Antiferro-Orbital Ordering with I4(1)/a Symmetry and Geometrical Frustration in the Spinel Vanadate MgV2O4

作者：Niitaka S^*; Ohsumi H; Sugimoto K; Lee S; Oshima Y; Kato K; Hashizume D; Arima T; Takata M; Takagi H

来源：Physical Review Letters, 2013, 111(26): 267201.

DOI：10.1103/PhysRevLett.111.267201

We conduct a detailed structural analysis of the S = 1 pyrochlore antiferromagnet MgV2O4, which exhibits an antiferromagnetic ordering marginally at T-N = 40 K, triggered by a structural transition from cubic to tetragonal symmetry at T-S = 62 K, using high resolution synchrotron x-ray diffraction and convergent beam electron diffraction. We reveal that the tetragonal phase below T-S has the symmetry of I4(1)/a and that the distortion pattern of VO6 octahedra is consistent with A-type antiferro-orbital ordering with alternating stacking of layers with yz/xy orbital chains and zx/xy orbital chains along the tetragonal c axis. This implies that an anisotropic coupling of V moments produced by the orbital ordering below T-S primarily brings about the antiferromagnetic ordering.

• 出版日期2013-12-26