Evidence of conventional superconductivity in single-crystalline MgCNi ₃

Despite the strong expectation for a ferromagnetic ground state in MgCNi₃, the real ground state shows superconductivity without any evidence of magnetism. In the electrical transport measurements on single-crystalline MgCNi₃, we found that the ferromagnetic spin fluctuation either did not exist or was very suppressed and that MgCNi ₃ could be well described by using the Bardeen-Cooper-Schrieffer theory. The evidence for this conclusion is as follows: (1) the normal-state resistivity could be explained by using the electron-phonon scattering model and (2) H_c2(T) near T_c was linear.