Superconducting Critical Field of Single-Crystal MO3Re

Critical field measurements were performed on a cylindrical rod of single-crystal ${\mathrm{Mo}}_3$Re. The isothermal, magnetic transitions were extremely sharp and reversible, indicating that the specimen was approaching nearly ideal properties. The principal data are: $T_c=9.80\mathrm{}°$K, $H_0=530\mathrm{}$ gauss, ${\left(\frac{d{H}_c}{\mathrm{dT}}\right)}_{T=T_c}=-114\mathrm{}$ gauss/deg. The deviation from parabolic behavior $D\left(t\right)\mathrm{}$ indicated a positive maximum value of 0.065. On the basis of this present work, we suggest a possible correlation between the thermodynamic critical field and the "filamentary" critical field noted for the high-field superconducting materials.