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Abstracts
O5.2
Pseudogap phenomena near the BKT transition of a two-dimensional
ultracold Fermi gas in the crossover region
M. Matsumoto, R. Hanai, D. Inotani, Y. Ohashi
Keio University, Faculty of Science and Technology, Department of Physics,
3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
We investigate a 2D Fermi gas near the Berezinskii-Kosterlitz-Thouless (BKT)
transition. Within the framework of a self-consistent T-matrix approximation,
we clarify how strong 2D pairing fluctuations cause pseudogap phenomena in the
low temperature region where the BKT transition has recently been observed in
a 6Li Fermi gas [Ries et al., PRL 114, 230401 (2015), and Murthy et al., PRL 115,
010401 (2015)]. We also discuss how these pairing fluctuations lead to bosonic
characters of this system in this regime. Since the BKT transition has recently
become a realistic hot topic in cold Fermi gas physics, our results would be useful
for the understanding of this unconventional Fermi superfluid.
O5.3
Towards high-temperature superfluidity of excitons in TMDC
Berman Oleg(1,2), Kezerashvili Roman(1,2)
1) Physics Department, New York City College of Technology, The City
University of New York, Brooklyn, NY 11201, USA
2) The Graduate School and University Center, The City University of New
York, New York, NY 10016, USA
Two-dimensional dipolar excitons, formed by electrons and holes, spatially
separated in two parallel transition metal dichalcogenide (TMDC) atomically
thin layers, form superfluid at temperatures below the critical one. The effective
masses of A and B dipolar excitons, collective excitations spectrum, sound velocity
and critical temperature Tc for superfluidity were obtained for various TMDC
bilayers. Tc for two-component exciton system in a TMDC bilayer is about
one order of magnitude higher than Tc for any one-component exciton system,
because for a two-component system Tc depends on the reduced mass of A and
B excitons, which is always smaller than the individual mass of A or B exciton.
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