Temperature dependence of London penetration depth anisotropy in superconductors with anisotropic order parameters

Journal Article · Fri Feb 05 00:00:00 EST 2021 · Physical Review. B

DOI:https://doi.org/10.1103/physrevb.103.054502· OSTI ID:1769023

Kogan, V. G.  ^[1]; Prozorov, R.  ^[2]

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1. Ames Lab., Ames, IA (United States)
2. Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States)

Here, we study the effects of anisotropic order parameters on the temperature dependence of London penetration depth anisotropy ${\gamma }_{\lambda }\left(T\right)$. After ${\mathrm{MgB}}_2$, this dependence is commonly attributed to distinct gaps on multiband Fermi surfaces in superconductors. We have found, however, that the anisotropy parameter may depend on temperature also in one-band materials with anisotropic order parameters $\mathrm{\Delta }(T,{\mathit{k}}_F)$; a few such examples are given. We have also found that for different order parameters, the temperature dependence of $\mathrm{\Delta }\left(T\right)/\mathrm{\Delta }\left(0\right)$ can be represented with good accuracy by the interpolation suggested by Einzel, which simplifies considerably the evaluation of ${\gamma }_{\lambda }\left(T\right)$. Of particular interest are mixed order parameters of two symmetries for which ${\gamma }_{\lambda }\left(T\right)$ may go through a maximum for a certain relative weight of two phases. Also, for this case we find that the ratio ${\mathrm{\Delta }}_{max}\left(0\right)/T_c$ may exceed substantially the weak-coupling limit of 1.76. It, however, does not imply strong coupling; rather, it is due to significantly anisotropic angular variation of $\mathrm{\Delta }$.

• Research Organization: Ames Laboratory (AMES), Ames, IA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division
• Grant/Contract Number: AC02-07CH11358
• OSTI ID: 1769023
• Report Number(s): IS-J-10,421; TRN: US2206686
• Journal Information: Physical Review. B, Vol. 103, Issue 5; ISSN 2469-9950
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY