Superconducting fluctuation in FeSe investigated by precise torque magnetometry

Abstract

We investigated the superconducting fluctuation in FeSe, which is assumed to be located in the BCS--BEC crossover region, via magnetic torque measurements. In our method, the absolute cantilever displacement is measured by detecting the interference intensity of the Fabry--Perot cavity formed between the cantilever and optical fiber. Our findings are totally different from the results of the previous torque magnetometry using a piezoresistive cantilever; the "giant" fluctuation diamagnetism related to the BCS--BEC crossover does not exist. Instead, a considerably smaller fluctuation signal originating from the vortex liquid was observed that showed a qualitatively similar behavior to those in cuprate superconductors. We also discuss the inconsistency between our torque data and the existence of a pseudogap proposed by an NMR experiment.

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Cited by in corpus (10)

• Exotic Superconducting States in FeSe-based Materials
• Preformed Cooper pairs in layered FeSe-based superconductors
• Spectroscopic Evidence of Superconductivity Pairing at 83 K in Single-Layer FeSe/SrTiO3 Films
• BCS-BEC Crossover and Pairing Fluctuations in a Two Band Superfluid/Superconductor: A T Matrix Approach
• Mechanism of screening or enhancing the pseudogap throughout the two-band Bardeen-Cooper-Schrieffer to Bose-Einstein condensate crossover
• Pseudogap and Strong Pairing Induced by Incipient and Shallow Bands in the Quasi-Two-Dimensional KCa${}_2$Fe${}_4$As${}_4$F${}_2$
• Superconductivity of the FeSe/SrTiO3 Interface in the View of BCS-BEC Crossover
• Studies of superconductivity of Fe chalcogenides in films grown by PLD technique
• Hidden Pseudogap and Excitation Spectra in a Strongly Coupled Two-Band Superfluid/Superconductor
• Onset Temperatures for Superconducting Fluctuations in Te-annealed FeTe${}_{1-x}$Se${}_x$ Single Crystals: Evidence for the BCS-BEC Crossover