Narrow Results

We measured the electrical resistivity under pressure for an antiferromagnet CeCoGe₃ without inversion symmetry in the tetragonal crystal structure. The Néel temperature T_N1 = 21 K at ambient pressure decreases monotonically with increasing pressure, and becomes zero at about 5.5 GPa. Superconductivity appears above 4.3 GPa, with a superconduting transition temperature T_sc = 0.72 K and a large upper critical field H_c2(0) = 7 T at 5.6 GPa. The large upper critical field H_c2(0)= 7 T exceeds the Pauli limitting field H_p (≃ 1.86T_sc)=1.3 T as in CePt₃Si, CeRhSi₃ and CeIrSi₃. The large slope of H_c2 at T_sc, -dH_c2/dT = 18T/K, at 5.6 GPa indicates the heavy-fermion superconductivity in CeCoGe₃.