Analysis ofH_c2(θ,T) for Mg(B_1−xC_x)₂single crystals by using the dirty two-gap model

Abstract

To understand the effect of carbon doping on the superconductivity in MgB(2), we obtained the angle- and temperature-dependent upper critical fields [H(c2)(θ) and H(c2)(T)] for Mg(B(1-x)C(x))(2) single crystals (x = 0.06 and 0.1) from resistivity measurements while varying the temperature, the field, and the direction of the field. The detailed values of the diffusivity for two different directions for each σ-band and π-band were obtained to explain both the temperature- and the angle-dependent H(c2) by using the dirty-limit two-gap model. The induced impurity scattering of the σ-band and the π-band for both the ab-plane and the c-direction is studied.

Intraband scattering rate and electronic diffusivity study in MgB2bulk samples

“…Since the angular dependence of the diffusivities can be written as (1.9 ± 0.4) × 10 −2 m 2 s −1 , η Bc2 = 88 ± 21 for the SiC-doped sample #B3. The diffusivity values of the two bands as well as their ratios are consistent with the upward curvature near T c of the B c2 versus T curves [38], with the T c values [58] and with previous studies on bulk and single crystals [59,56,60]. Anyway further investigations are planned in order to verify if the B c2 versus T curves keep their positive curvature in the overall temperature range [61].…”