Transition from magnetic to nonmagnetic ground state in a heavy-fermion compound Ce7Ni3 under high pressure.

The electrical resistivity and ac magnetic susceptibility of the heavy-fermion compound Ce7Ni3 were measured in the temperature range from 0.4 to 300 K and in the pressure range up to 1.5 GPa. The Néel temperature of 1.9 K for antiferromagnetic transition at ambient pressure decreases with increasing pressure and vanishes at about 0.33 GPa. The magnetic resistivity, rm5r~Ce7Ni3)-r(La7Ni3), decreases steeply with pressure, and above 0.66 GPa, rm(T) can be described by the expression rm(T)5rm(0)1AT . The coefficient A decreases and the temperature range in which the T dependence is held becomes wider with increasing pressure. The electronic Grüneisen parameter for the Kondo temperature TK , 2] lnTK /] lnV, is evaluated to be 132 from the pressure dependence of A . This value is larger than that of typical heavy-fermion compounds. The results are discussed in relation to the competition between the magnetic interaction and the Kondo interaction in Ce7Ni3 . @S0163-1829~96!03326-7#