Non-resonant microwave absorption studies of superconducting $MgB_2$ and $MgB_2+ MgO$

Joshi, Janhavi P and Sarangi, Subhasis and Sood, AK and Pal, Dilip and Bhat, SV (2002) Non-resonant microwave absorption studies of superconducting $MgB_2$ and $MgB_2+ MgO$. In: Pramana: Journal of Physics, 58 (2). pp. 361-369.

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Abstract

Non-resonant microwave absorption (NRMA) studies of superconducting $MgB_2$ and a sample containing $\sim10$% by weight of MgO in $MgB_2$ are reported. The NRMA results indicate near absence of intergranular weak links in the pure $MgB_2$ sample. A linear temperature dependence of the lower critical field $H_c_1$ is observed indicating a non-s wave superconductivity. However, the phase reversal of the NRMA signal which could suggest d wave symmetry is also not observed. In the $MgB_2+ MgO $sample, much larger low field dependent absorption is observed indicating the presence of intergranular weak links. The hysteretic behavior of NRMA is compared and contrasted in the two samples. In the pure $MgB_2$ sample, a large hysteresis is observed between the forward and the reverse scans of the magnetic field indicating strong pinning of flux lines. This hysteresis saturates a few degrees below $T_c$ while in the $MgB_2 + MgO$ sample, a much slower increase of hysteresis with decreasing temperature is observed, a signature of weaker pinning.

Item Type:	Journal Article
Publication:	Pramana: Journal of Physics
Publisher:	Indian Academy of Science
Additional Information:	Copyright of this article belongs to Indian Academy of Sciences.
Keywords:	Microwave absorption;Superconductivity
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	02 Jun 2006
Last Modified:	19 Sep 2010 04:28
URI:	http://eprints.iisc.ac.in/id/eprint/7415

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