Non-resonant microwave absorption(NRMA) studies of superconducting MgB_2 at a frequency of 9.43 GHz in the field range -50 Gauss to 5000 Gauss are reported. The NRMA results indicate near absence of intergranular weak links. A linear temperature dependence of the lower critical field H_c1 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.
@article{arxiv.cond-mat/0103369,
title = {Non-resonant microwave absorption studies of superconducting MgB_2},
author = {Janhavi P. Joshi and Subhasis Sarangi and A. K. Sood and S. V. Bhat and Dilip Pal},
journal= {arXiv preprint arXiv:cond-mat/0103369},
year = {2009}
}