IGOR ZALIZNYAK
BROOKHAVEN NATIONAL LABORATORY
TEMPERATURE INDUCED MAGNETISM, LATTICE AND ORBITAL ORDER IN IRON TELLURIDE
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 B 85, 085105 (2012); also unpublished (2013).
Host: Prof. G. Kotliar