scholarly journals Evidence of pair-density wave in spin-valley locked systems

2019 ◽  
Vol 5 (3) ◽  
pp. eaat4698
Author(s):  
Jordan Venderley ◽  
Eun-Ah Kim

Cooper pairs with a finite center-of-mass momentum form a remarkable state in which the superconducting order parameter is modulated periodically in space. Although intense interest in such a “pair-density wave” (PDW) state has emerged due to recent discoveries in highTcsuperconductors, there is little theoretical understanding of the mechanism driving this exotic state. The challenge is that many competing states lie close in energy in seemingly simple models, such as the Hubbard model, in the strongly correlated regime. Here, we show that inversion symmetry breaking and the resulting spin-valley locking can promote PDWs over more commonly found spin stripes through frustration against magnetic order. Specifically, we find the first robust evidence for a PDW within density matrix renormalization group simulation of a simple fermionic model. Our results point to a tantalizing possibility in hole-doped group VI transition metal dichalcogenides, with spin-valley locked band structure and moderate correlations.

2021 ◽  
Author(s):  
Chandan Setty ◽  
Laura Fanfarillo ◽  
Peter Hirschfeld

Abstract In weakly coupled BCS superconductors, only electrons within a tiny energy window around the Fermi energy, EF, form Cooper pairs. This may not be the case in strong coupling superconductors such as cuprates, FeSe, SrTiO3 or cold atom condensates where the pairing scale, EB, becomes comparable or even larger than EF. In cuprates, for example, a plausible candidate for the pseudogap state at low doping is a fluctuating pair density wave, but no microscopic model has yet been found which supports such a state. In this work, we write an analytically solvable model to examine pairing phases in the strongly coupled regime and in the presence of anisotropic interactions. Already for moderate coupling we find an unusual finite temperature phase, below an instability temperature Ti, where local pair correlations have non-zero center-of-mass momentum but lack long-range order. At low temperature, this fluctuating pair density wave can condense either to a uniform d-wave super- conductor or the widely postulated pair-density wave phase depending on the interaction strength. Our minimal model offers a unified microscopic framework to understand the emergence of both fluctuating and long range pair density waves in realistic systems.


2020 ◽  
Vol 124 (1) ◽  
Author(s):  
A. J. Shook ◽  
V. Vadakkumbatt ◽  
P. Senarath Yapa ◽  
C. Doolin ◽  
R. Boyack ◽  
...  

2019 ◽  
Vol 32 (9) ◽  
pp. 2745-2749 ◽  
Author(s):  
Shiping Feng ◽  
Deheng Gao ◽  
Yiqun Liu ◽  
Yingping Mou ◽  
Shuning Tan

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhenzhong Shi ◽  
P. G. Baity ◽  
J. Terzic ◽  
T. Sasagawa ◽  
Dragana Popović

2015 ◽  
Vol 91 (5) ◽  
Author(s):  
D. F. Agterberg ◽  
Drew S. Melchert ◽  
M. K. Kashyap

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