We report microwave surface impedances of FeSe0.4Te 0.6 single crystals measured at 12, 19, and 44 GHz. The penetration depth exhibits a power-law behavior, δλL= λL(T)-λL(0) CTn with an exponent n2, which is considered to result from impurity scattering. The temperature dependence of the superfluid density largely deviates from the behavior expected in the BCS theory. We believe that this deviation is caused by the crossover from the dirty regime near Tc to the clean regime at low temperatures, which is supported by the rapid increase of the quasiparticle scattering time obtained from the microwave conductivity. We also believe that the previously published data of the superfluid density can be interpreted in this scenario.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2011 Oct 18|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics