Enhanced physical properties of single crystal Fe0.99Te0.63Se0.37 prepared by self-flux synthesis method

Abstract

In this study, we have systemically studied the physical, electrical and magnetic properties of Fe0.99Te0.63Se0.37 single crystalline samples prepared by self-flux method. We found that the self-flux method is a suitable synthesis technique for this alloys if setting of experimental parameters made carefully. The M-H curve affirms that samples are typical type-II superconductor. Strong sign of bulk superconductivity, even after high field measurements, were seen. Calculated Jcmag values, at zero field, were found to be 7.7 × 105 Acm−2 and 2.6 × 104 Acm−2 for 5 K and 10 K respectively. The upper critical field Hc2(0) has been determined with the magnetic field parallel to the sample surface and yielding a maximum value of 65 T. At the zero field coherence length, ξ, value was calculated to be 2.24 nm for 10% Tcoffset which is significantly larger (approximately 6 fold) than the unit cell, a, and indicating the absence of weak link behavior in the sample. Calculated μ0Hc2(0)/kBTc rate indicated comparably higher value (3.66 T/K) than the Pauli limit (1.84 T/K) and obtained results were suggested unconventional nature of superconductivity in our samples.