The field-induced magnetic phase in a heavy-fermion antiferromagnet, Ce7Ni3

Abstract

In the heavy-fermion antiferromagnet Ce7Ni3with three nonequivalent Ce sites (CeI, CeII, CeIII),a field-induced magnetic (FIM) phase has been found in the fieldregion above 0.7 T with the field applied along the hexagonalc-axis.Magnetoresistance, specific heat, and magnetization measurements showed thatthe FIM phase is separated from the spin-density-wave phase present below0.3 T. The separation is attributed to large spin fluctuations on CeIII,which originate from a geometrical frustration in the quasiregular tetrahedron made of CeI and CeIII.