Tuesday, July 30, 2013

1307.7162 (David Fobes et al.)

Ferro-orbital ordering transition in iron telluride Fe$_{1+y}$Te ($y =

David Fobes, Igor A. Zaliznyak, Zhijun Xu, Ruidan Zhong, Genda Gu, John M. Tranquada, Leland Harriger, Deepak Singh, V. Ovidiu Garlea, Mark Lumsden, Barry Winn
Fe$_{1+y}$Te with $y \lesssim 0.05$ exhibits a first-order phase transition on cooling to a state with a lowered structural symmetry, bicollinear antiferromagnetic order, and metallic conductivity, $d\rho/dT > 0$. Here, we study samples with $y = 0.09(1)$, where the frustration effects of the interstitial Fe decouple different orders, leading to a sequence of transitions. While the monoclinic lattice distortion is closely followed by \emph{incommensurate} magnetic order, the development of \emph{bicollinear} order and metallic electronic coherence is uniquely associated with a separate hysteretic first-order transition to a bond-order wave (BOW) phase at a markedly lower temperature. The BOW state suggests ferro-orbital ordering, where electronic delocalization in ferromagnetic zigzag chains decreases local spin and results in metallic transport.
View original: http://arxiv.org/abs/1307.7162

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