Collapse of peak effect by alternating current and its frequency dependence in MgCNi3 single crystal
ORAL
Abstract
The peak effect, which appears as sharp rise in critical current near superconductor-normal transition of a superconductor, is first order phase transition. However, if vortices happen to move across sample by direct current (DC), sharp transition nature becomes blunted by edge contamination as intensively studied in NbSe$_{2}$. This edge contamination has been shown to be removed by alternating current (AC) or by using edgeless Corbino geometry. Among few superconducting materials showing peak effect, MgCNi$_{3}$ exhibits fairly sharp peak effect even in DC strip geometry. And remarkably, critical current measured by using AC is greatly suppressed as frequency of AC increases.
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