Temperature- and magnetic-field-dependent resistivity of MgB₂ sintered at high-temperature and high-pressure condition

We report the temperature- and magnetic-field-dependent resistivity of MgB₂ sintered at high-temperature and high-pressure condition. The superconducting transition width for the resistivity measurement was about 0.4 K, and the low-field magnetization showed a sharp superconducting transition with a transition width of about 1 K. The resistivity in the normal state roughly followed T² behavior with smaller residual resistivity ratio (RRR) of 3 over broad temperature region above 100 K rather than reported T³ behavior with larger RRR value of ∼20 in the samples made at lower pressures. Also, the resistivity did not change appreciably with the applied magnetic field, which was different from previous report. These differences were discussed with the microscopic and structural change due to the high-pressure sintering.