Resonance in-plane magnetic field effect as a means to reveal the Fulde-Ferrell-Larkin-Ovchinnikov state in layered superconductors

Abstract

The vector potential of a parallel magnetic field produces a modulation of the interlayer coupling between adjacent superconducting layers. In some cases the period of this modulation can coincide with the period of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) modulation of the superconducting order parameter. Such a resonance condition results in cusps on the temperature and in-plane angular dependencies of the upper critical field H c2. This effect can open up a possibility to unambiguously evidence a spatially modulated superconducting phase in layered conductors. Remarkably, the proposed signature of the FFLO state is directly based on the main feature of the FFLO state, the spatial modulations of the order parameter.

In Search of Unambiguous Evidence of the Fulde–Ferrell–Larkin–Ovchinnikov State in Quasi-Low Dimensional Superconductors

“…of Equation (30) is of the same order as the corresponding term in Equation (29) (up to the second order with respect to t/T c0 ). Consequently, ∆ ±2 becomes on the order of ∆ 0 , and one has to consider both equations in the system on equal footing [81]. Figure 7 displays the change of the transition temperature, ∆T c = T c − T cP , due to the orbital effects of the applied magnetic field as a function of the reduced temperature for different field orientations.…”

Peculiarities of the orbital effect in the Fulde-Ferrell-Larkin-Ovchinnikov state in quasi-one-dimensional superconductors

“…[32] and making use of the definition for the order parameter function, Eqs. (3) and (4), we obtain two systems of coupled equations:…”

“…The NMR measurements as well as the anomalous in-plane anisotropy of the upper critical field [3,31] in the organic compound (TMTSF) 2 ClO 4 favor, for a magnetic field parallel to the conducting chains, the existence of FFLO state with a spin singlet pairing. Moreover, it has been shown within the layered superconductor model under the applied in-plane magnetic field in the FFLO phase that the experimentally observed anomalous field-direction dependence of the upper critical field [3] as well as the anomalous cusps in this dependence due to resonances between the modulation wave vector and the vector potential can serve as a direct evidence for the appearance of the FFLO phase in layered superconductors [32][33][34][35]. This peculiar behavior of the in-plane anisotropy of the FFLO phase completes the anomalous oscillatory out-of-plane angular dependence of the critical field in FFLO state [36][37][38][39][40].…”

Holographic entanglement entropy in imbalanced superconductors

“…For this reasons the imbalanced systems has been studied vigorously -both theoretically and experimentally. Theoretical studies on imbalanced systems often focus on the possibility of exploring imbalanced superconducting states in different JHEP01 (2014)136 physical systems, for example, in population-imbalanced Ultracold atomic gases [38,[40][41][42], optical lattices [43], heavy-fermionic superconductor CeCoIn 5 [44], two-dimensional organic superconductors [37,39,45,46] and quark matter core of the neutron stars [47,48]. The experimental search is a topic of vigorous research till date as it is very hard to pinpoint this state in the phase diagram.…”