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Temperature Induced Magnetism, Lattice and Orbital Order in Iron Telluride


Tuesday, January 21, 2014, 01:30pm - 02:30pm

Recent neutron scattering measurements [1] have revealed an unusual temperature-induced enhancement of dynamical magnetism in iron telluride, FeTe, the parent material of the chalcogenide family of iron-based superconductors. A peculiar pattern of low-energy magnetic scattering, characteristic of a quantum spin liquid was observed, which was found to be anomalously suppressed with the decreasing temperature. While these findings were consistent with both Kondo-like screening of local spin fluctuations by conduction electrons, or a delocalization, on cooling, of one of the electrons giving rise to local spin, our more recent results shed light on this issue, favoring the latter scenario. We investigate the magneto-structural phase diagram of Fe1+yTe, y ≈ 0.09, where the first-order phase transition to a monoclinically distorted phase with the "bicollinear" antiferromagnetic order observed for y < 0.05 is split into a sequence of transitions due to the frustrating effect of extra iron [2]. By combining results of bulk characterization of electronic behavior and the diffraction data on the microscopic structural changes we are able to disentangle different low-temperature orders and identify new, electronically driven ferro-orbital ordering transition associated with the formation of zigzag Fe-Fe chains. The newly discovered orbital ordering is similar to that in manganites, and has profound effect on magnetic and electronic properties. This work was supported by the US DOE under Contract DE-AC02-98CH10886.

[1] I. A. Zaliznyak, Z. J. Xu, J. M. Tranquada, G. D. Gu, A. M. Tsvelik, M. B. Stone, Phys. Rev. Lett. 107, 216403 (2011).

[2] I. A. Zaliznyak, Z. J. Xu, J. S. Wen, J. M. Tranquada, G. D. Gu, V. Solovyov, V. N. Glazkov, A. I. Zheludev, V. O. Garlea, M. B. Stone, Phys. Rev. B 85, 085105 (2012); also unpublished (2013).


Location:   Serin Physics 385
Speaker:   Igor Zaliznyak, Brookhaven National Laboratory

Host: Professor G. Kotliar