Superconducting fluctuations in FeSe investigated by precise torque magnetometry

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-Pérot cavity formed between...

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Bibliographic Details
Published in:Physical review. B 2019-02, Vol.99 (6), p.060503(R), Article 060503
Main Authors: Takahashi, Hideyuki, Nabeshima, Fuyuki, Ogawa, Ryo, Ohmichi, Eiji, Ohta, Hitoshi, Maeda, Atsutaka
Format: Article
Language:English
Subjects:
Crossovers
Diamagnetism
Magnetic measurement
NMR
Nuclear magnetic resonance
Optical fibers
Superconductivity
Torque
Variation
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Summary: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-Pérot cavity formed between the cantilever and optical fiber. Our findings are different from the results of previous torque magnetometry studies 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 qualitatively similar behavior to that in cuprate superconductors. We also discuss the inconsistency between our torque data and the existence of a pseudogap proposed by an NMR experiment.
ISSN:2469-9950
2469-9969
DOI:10.1103/PhysRevB.99.060503