Linear temperature-dependence of penetration depth due to phase fluctuations

Coexistence of diagonal and off-diagonal long-range order: A Monte Carlo study

“…The mean-field phase diagram of ref. [5] is qualitatively confirmed. However, our simulations indicate that the supersolid phase is smaller than one would deduce from mean-field theory.…”

“…In these arrays hopping, Coulomb interactions and the chemical potential may be tuned independently and therefore they constitute an ideal system for investigating a supersolid phase. Moreover, the Cooper pairs in JJA's are soft-core bosons that have a larger coexistence region than hard-core bosons as was demonstrated on the mean-field level by Roddick and Stroud [5].…”

“…Normally bosons at zero temperature are either superfluid (with off-diagonal LRO) or solid (with diagonal LRO). However, for a finite range of the interactions between the bosons a coexistence phase was predicted within a mean-field approximation [2][3][4][5]. Experiments have been performed on 4 He, but no positive identification of this coexistence phase (often called supersolid) has yet been made.…”

“…To gain understanding of the zero temperature properties of the model described by the Hamiltonian (1), we first discuss the mean-field phase diagram following Roddick and Stroud [5]. The phase diagram is shown in figure 1 a) and b) for U 1 /U 0 =0.125 and 0.2 respectively.…”

Superfluid suppression ind-wave superconductors due to disordered magnetism

“…A number of authors 7,8 have suggested that T c is governed by phase fluctuations, possibly in combination with quasiparticle excitations 9 , and in particular that the rapid collapse of ρ s and T c at p c can be thus explained 10 . In this work, we examine a completely different mechanism: the suppression of superfluidity by the formation of static magnetic moments.…”