In-plane electrical transport properties of MgB2 single crystals grown under high pressure of 4-6 GPa and temperature of 1400-1700oC in Mg-B-N system have been measured. For all specimens we found sharp superconducting transition around 38.1-38.3K with transition width within 0.2-0.3K. Estimated resistivity value at 40K is about 1 mkOhmcm and resistivity ratio R(273K)/R(40K) of about 4.9. Results of measurements in magnetic field up to 5.5T perpendicular to Mg and B planes and up to 9T in parallel orientation show temperature dependent anisotropy of the upper critical field with anisotropy ratio increasing from 2.2 close to Tc up to about 3 below 30K. Strong deviation of the angular dependence of Hc2 from anisotropic mass model has been also found.
@article{arxiv.cond-mat/0202133,
title = {Anisotropic Superconducting Properties of MgB2 Single Crystals},
author = {Yu. Eltsev and S. Lee and K. Nakao and N. Chikumoto and S. Tajima and N. Koshizuka and M. Murakami},
journal= {arXiv preprint arXiv:cond-mat/0202133},
year = {2009}
}
Comments
10pages, including 5 figures,submitted to Physica C (in press)