Magnetic rapid quench measurement in U(1) and SU(2) superconductors

We observed the power law and the critical exponent of quantum phase transitions by measuring a transient response in an Al/AlOx/Al junction of U(1) superconductors and Sr2RuO4 single crystals of SU(2) superconductors, when magnetic field decreased rapidly from more than the critical field to zero magnetic field below T = 0.1 K. In the Al/AlOx/Al junction, the result shows that the domain length xi is a power function of the quench time tau(Q). The critical exponent is 0.30 +/- 0.01. Moreover, in the Sr2RuO4 crystal, the result shows xi is a power function of tau(Q) and the critical exponent is 0.40 +/- 0.01. From the results of U(1) and SU(2) superconductors, we consider the critical exponents observed by the quenching are derived by a mean-field value in charged systems. Using typical U(1) and SU(2) superconductors, we find that the magnetic quench is efficient method to study formation processes of topological defects for a quantum phase transition near T = 0. http://iopscience.iop.org/article/10.1088/1742-6596/150/5/052187/pdf