Orbital Effect on FFLO Phase and Energy Dissipation due to Vortex Dynamics in Magnetic-Field-Induced Superconductor λ-(BETS)₂FeCl₄

Abstract

Resistance measurements have been performed for a two-dimensional magnetic-field-induced superconductor λ-(BETS)2FeCl4, where BETS denotes bis(ethylenedithio)tetraselenafulvalene. In magnetic fields along the \(c\)-axis (parallel to the conducting layers), characteristic dip structures in the interlayer resistance are observed up to 24.2 T, ascribed to the commensurability effect between the Josephson vortex lattice and periodic oscillation of the order parameter of the Fulde and Ferrell, and Larkin and Ovchinnikov (FFLO) phase. The dip structures disappear when the magnetic field is tilted from the layers only by 1°, showing that the FFLO phase is removed by the orbital effect. When the field is nearly parallel to the layers, the resistance in the superconducting state becomes significantly larger than the normal state value, showing the presence of peculiar vortex dynamics.