Peak-effect of NbN diffusion wires under hydrostatic pressure

Superconducting NbN wires with stoichiometric composition show a pronounced maximum in the critical current curves just below Bc2. This behavior is called peak-effect. For the first time critical currents of such samples have been measured under hydrostatic pressure as a function of the magnetic induction. There is no significant change in the critical current at lower fields up to 8 T, where the peak starts to arise. A small but systematic shift of the peak maxima to lower inductions with increasing pressure is observed. Also the upper critical inductions Bc2change slightly under pressure to lower magnetic inductions. In the reduced plot of the quenching curves (Icvs.b=B/Bc2) the peak maxima for different pressures occur at constant reduced induction bp=0.8.