Amplitude, phase, and topological fluctuations shaping the complex phase diagram of two-dimensional superconductors

Year: 2024

Authors: Furutani K., Midei G., Perali A., Salasnich L.

Autors Affiliation: Nagoya Univ, Dept Appl Phys, Nagoya 4648603, Japan; Nagoya Univ, Inst Adv Res, Nagoya 4648601, Japan; Univ Camerino, Sch Sci & Technol, Phys Div, Via Madonna delle Carceri 9, I-62032 Camerino, Italy; Univ Camerino, Sch Pharm, Phys Unit, Via Madonna delle Carceri 9, I-62032 Camerino, Italy; Univ Padua, Dipartimento Fis & Astron Galileo Galilei, via Marzolo 8, I-35131 Padua, Italy; Univ Padua, QTech Ctr, Via Marzolo 8, I-35131 Padua, Italy; Ist Nazl Fis Nucl, Sez Padova, Via Marzolo 8, I-35131 Padua, Italy; CNR, Ist Nazl Ott, Via Carrara 2, I-50019 Sesto Fiorentino, Italy.

Abstract: We study the amplitude and phase fluctuations of the Ginzburg-Landau quasiorder parameter for superconductors in two spatial dimensions. Starting from the mean-field critical temperature T-c0, we calculate the beyond-mean-field critical temperature T-c by including thermal fluctuations of the quasiorder parameter within the Gaussian level. Moreover, from our beyond-mean-field results, we derive the Berezinskii-Kosterlitz-Thouless critical temperature T-BKT, which takes into account topological vortex-antivortex excitations in the phase fluctuations as well as the amplitude fluctuations, to obtain the shifts of transition temperatures. We elucidate how the Gaussian thermal fluctuations and phase fluctuations associated with vortex excitations affect thermodynamic properties by determining the H-T phase diagram for a type-II superconductor and computing the critical behaviors of the heat capacity, which are experimentally accessible, allowing the characterization of the cascade of different kinds of fluctuations in 2D superconductors.

Journal/Review: PHYSICAL REVIEW B

Volume: 110 (13)      Pages from: 134501-1  to: 134501-14

More Information: The authors thank A. A. Varlamov for the useful comments. This work has been partially supported by PNRR MUR project PE0000023-NQSTI. K.F. was supported by JSPS KAKENHI (Grant No. JP24K22858) and Maki Makoto Foundation.
KeyWords: Transition; Bcs; Temperature; Pseudogap; Crossover; Density; Gas
DOI: 10.1103/PhysRevB.110.134501