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Register a new userTemperature Dependence of the Magnetic Penetration Depth in the Vortex State of the Pyrochlore Superconductor, Cd2Re2O7
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We report transverse field and zero field muon spin rotation studies of the superconducting rhenium oxide pyrochlore, Cd2Re2O7. Transverse field measurements (H=0.007 T) show line broadening below Tc, which is characteristic of a vortex state, demonstrating conclusively the type-II nature of this superconductor. The penetration depth is seen to level off below about 400 mK (T/Tc~0.4), with a rather large value of lambda (T=0)~7500A. The temperature independent behavior below ~ 400 mK is consistent with a nodeless superconducting energy gap. Zero-field measurements indicate no static magnetic fields developing below the transition temperature.
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We report temperature- and magnetic field-dependent bulk muon spin rotation measurements in a c-axis oriented superconductor CaC6 in the mixed state. Using both a simple second moment analysis and the more precise analytical Ginzburg-Landau model, we obtained a field independent in-plane magnetic penetration depth {lambda}ab (0) = 72(3) nm. The temperature dependencies of the normalized muon spin relaxation rate and of the normalized superfluid density result to be identical, and both are well represented by the clean limit BCS model with 2Delta/kB Tc = 3.6(1), suggesting that CaC6 is a fully gapped BCS superconductor in the clean limit regime.
In the tetragonal heavy fermion system CeCoIn5 the unconventional superconducting state is probed by means of muon spin rotation. The pressure dependence (0-1 GPa) of the basal-plane magnetic penetration depth (lambda_a), the penetration depth anisotropy (gamma=lambda_c/lambda_a) and the temperature dependence of 1/lambda_i^2 (i=a,c) were studied in single crystals. A strong decrease of lambda_a with pressure was observed, while gamma and lambda_i^2(0)/lambda_i^2(T) are pressure independent. A linear relationship between 1/lambda_a^2(270 mK) and Tc was also found. The large decrease of lambda_a with pressure is the signature of an increase of the number of superconducting quasiparticles by a factor of about 2.
The temperature dependence of the in-plane, lambda_{parallel}, and interplane, lambda_{perp}, London penetration depth was measured in the metal-free all-organic superconductor beta-ET (see title) ($T_c approx$ 5.2 K). lambda_{parallel} ~T^3 up to 0.5 Tc, a power law previously observed only in materials thought to be p-wave superconductors. lambda_{perp} is larger than the sample dimensions down to the lowest temperatures (0.35 K), implying an anisotropy of lambda_{perp}/lambda_{parallel} ~ 400-800.
We study the temperature dependence of the magnetic penetration depth in a 3D topological superconductor (TSC), incorporating the paramagnetic current due to the surface states. A TSC is predicted to host a gapless 2D surface Majorana fluid. In addition to the bulk-dominated London response, we identify a $T^3$ power-law-in-temperature contribution from the surface, valid in the low-temperature limit. Our system is fully gapped in the bulk, and should be compared to bulk nodal superconductivity, which also exhibits power-law behavior. Power-law temperature dependence of the penetration depth can be one indicator of topological superconductivity.
One of the features of the unconventional $s_pm$ state in iron-based superconductors is possibility to transform to the $s_{++}$ state with the increase of the nonmagnetic disorder. Detection of such a transition would prove the existence of the $s_pm$ state. Here we study the temperature dependence of the London magnetic penetration depth within the two-band model for the $s_pm$ and $s_{++}$ superconductors. By solving Eliashberg equations accounting for the spin-fluctuation mediated pairing and nonmagnetic impurities in the $T$-matrix approximation, we have derived a set of specific signatures of the $s_pm to s_{++}$ transition: (1) sharp change in the behavior of the penetration depth $lambda_{L}$ as a function of the impurity scattering rate at low temperatures; (2) before the transition, the slope of $Delta lambda_{L}(T) = lambda_{L}(T)-lambda_{L}(0)$ increases as a function of temperature, and after the transition this value decreases; (3) the sharp jump in the inverse square of the penetration depth as a function of the impurity scattering rate, $lambda_{L}^{-2}(Gamma_a)$, at the transition; (4) change from the single-gap behavior in the vicinity of the transition to the two-gap behavior upon increase of the impurity scattering rate in the superfluid density $rho_{s}(T)$.
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