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

V. G. Kogan; R. Prozorov

doi:10.1103/PhysRevB.103.054502

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

V. G. Kogan, R. Prozorov

DOI 10.1103/PhysRevB.103.054502 · Physical Review B

T1

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Abstract

We study the effects of anisotropic order parameters on the temperature dependence of London penetration depth anisotropy γλ(T). After MgB2, 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 Δ(T,kF); a few such examples are given. We have also found that for different order parameters, the temperature dependence of Δ(T)/Δ(0) can be represented with good accuracy by the interpolation suggested by Einzel [J. Low Temp. Phys 131, 1 (2003)], which simplifies considerably the evaluation of γλ(T). Of particular interest are mixed order parameters of two symmetries for which γλ(T) may go through a maximum for a certain relative weight of two phases. Also, for this case we find that the ratio Δmax(0)/Tc 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 Δ.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown