Magnetic penetration-depth measurements of a suppressed superfluid density of superconducting Ca0.5Na0.5Fe2As2 single crystals by proton irradiation

Article

关键词: D-WAVE SUPERCONDUCTORS;    HEAVY-FERMION SUPERCONDUCTORS;    UNCONVENTIONAL SUPERCONDUCTORS;    ANISOTROPIC SUPERCONDUCTORS;    CUPRATE SUPERCONDUCTORS;    CRITICAL-TEMPERATURE;    IMPURITY SCATTERING;    II SUPERCONDUCTORS;    LEVITATION FORCE;    YBA2CU3O7-DELTA;   

DOI  :  10.1103/PhysRevB.86.144509

来源: SCIE

【 摘 要 】

We report on the dramatic effect of random point defects, produced by proton irradiation, on the superfluid density rho(s) in superconducting Ca0.5Na0.5Fe2As2 single crystals. The magnitude of the suppression is inferred from measurements of the temperature-dependent magnetic penetration depth lambda(T) using magnetic force microscopy. Our findings indicate that a radiation dose of 2 x 10(16) cm(-2) produced by 3 MeV protons results in a reduction of the superconducting critical temperature T-c by approximately 10%. In contrast, rho(s)(0) is suppressed by approximately 60%. This breakdown of the Abrikosov-Gorkov theory may be explained by the so-called Swiss cheese model, which accounts for the spatial suppression of the order parameter near point defects similar to holes in Swiss cheese. Both the slope of the upper critical field and the penetration depth lambda(T/T-c)/lambda(0) exhibit similar temperature dependences before and after irradiation. This may be due to a combination of the highly disordered nature of Ca0.5Na0.5Fe2As2 with large intraband and simultaneous interband scattering as well as the s(+/-)-wave nature of short coherence length superconductivity.

【 授权许可】

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