Successive magnetic transition in non-centrosymmetric CeCoGe3 probed by Co-NQR

Co-NQR measurements for non-centrosymmetric superconductor CeCoGe3 have been performed in ambient and under pressure up to 1.5 GPa to investigate the magnetic structures for the successive magnetic transition at T-N1=21 K, T-N2=12 K and T-N3=8 K. In ambient pressure, the crystallographically equivalent one Co site becomes three sites at T-N1 > T > T-N2, and further becomes four sites at T-N2 > T. Applying pressure at 4.2 K, the four Co sites becomes two sites above 0.3 Gpa. These Co sites acquire slightly different internal field parallel to the c-axis, consistent with the anisotropic magnetization with easy c-axis. The T-dependences of the internal fields and the spectral weights for respective sites are estimated. The magnetic structure in each phase is discussed referring to the recent results of neutron scattering.