Thermal excitation measured by resistivity measurement on the Mg-doped high temperature superconductors

The thermal excitation that starts to occur from the opening temperature T* in the normal state of Mg-doped YBCO superconductors was studied by the resistivity measurement. There are some characteristic temperatures T* and T_F related to the thermal excitation of quasi-particles during the cooling process. The data of T_F are close to the onset temperature of the superconductors. The magnitude of the pseudo-gap (Δ_PO) can be measured from the ln[1/_ρN(T)-1/ρ(T] vs 1/T curve, it depends on the concentration of the magnesium.