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Binghamton University
Department of Physics, Applied Physics and Astronomy
PHYSICS COLLOQUIUM
“Effects of Orbital Ordering on Superconductivity and Spin Fluctuations in FeSe”
Dr. Shantanu Mukherjee
Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark
/ Department of Physics, Binghamton University
Abstract:
FeSe is currently one of the most hotly debated iron-based systems due in part to its very high Tc when
monolayers are placed on STO substrates, and in part due to the fact that the material exhibits a structural
distortion near TS ~ 90K without any concomitant magnetic order. In addition, undoped bulk FeSe samples,
which become superconducting below T~8K, display evidence of orbital ordering setting in near TS. I will
discuss the normal and superconducting properties of FeSe using a tight-binding model [1], and include the
effect of orbital ordering. The model reproduces the essential features of FeSe band structure seen in ARPES
and quantum oscillation experiments [2]. Using this model, the spin lattice relaxation rate is calculated and the
results are compared with recent NMR experiments [3]. We next discuss the structure of the spin fluctuations
seen in inelastic neutron scattering experiments [4] and consequences of a spin fluctuation mediated
superconducting pairing in FeSe and the resulting gap structure. Finally, the density of states derived from our
calculations is compared to STM experiments [5].
[1] Shantanu Mukherjee et al., Phys. Rev. Lett. 115, 026402 (2015).
[2] Watson et al., Phys. Rev. B 91, 155106 (2015).
[3] S.-H. Baek, et al., Nature Materials 14, 210 (2014).
[4] Rahn et al., Phys. Rev. B 91, 180501 (2015).
[6] C. L. Song et al., Science 332, 1410 (2010).
Monday, October 05, 2015
Science Library Room 212
PRESENTATION 11:00 PM– 12:00PM
ALL WELCOME – COFFEE AND REFRESHMENTS AT 10:50am