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Peak effect in single crystal MgB$_2$ superconductor for ${\bf H}\parallel c$-axis

M. Pissas·S. Lee·A. Yamamoto·S. Tajima
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Abstract

We have studied the phase diagram of MgB$_2$ superconductor using a single crystal for ${\bf H}\parallel c$-axis. For the first time we report the existence of peak effect in the screening current in MgB$_{2}$ single crystal for ${\bf H}\parallel c$-axis. In the magnetic field regime $10<H<13.5$ kOe the local fundamental diamagnetic moment displays a very narrow diamagnetic step, with a temperature width of the same size as the zero dc-magnetic field transition. For higher field this step is transformed to a peak which is related with the peak effect in the screening current. Finally, for $H<10$ kOe the diamagnetic step is transformed to a gradual transition. Our findings for the vortex matter phase diagram for the MgB$_2$ are closely related with theoretical predictions concerning the vortex matter phase diagram of a type II superconductor in the presence of weak point disorder.

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M. Pissas, S. Lee, A. Yamamoto, S. Tajima. 2002-05-27. Peak effect in single crystal MgB$_2$ superconductor for ${\bf H}\parallel c$-axis. https://doi.org/10.1103/physrevlett.89.097002

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