Suppression of magnetic order in [formula omitted] by magnetic fields

Abstract

The heavy-fermion compound YbNiSi 3 orders antiferromagnetically below the Néel temperature T N = 5.1 K . The magnetic order can be suppressed either by applying a magnetic field of B c = 8.3 T (for B ∥ b ) or by replacing Si with Ge. The latter is equivalent to a negative lattice pressure. In search of a field-induced quantum phase transition, we studied the disappearance of magnetic order in YbNiSi 3 at B c , using specific-heat and resistivity measurements. Apart from a slightly enhanced specific heat and resistivity at B c , no signs for quantum criticality could be identified down to 0.35 K. Our data indicate that YbNiSi 3 belongs to the heavy-fermion compounds in which the magnetic field gradually reduces the amount of antiferromagnetic order until the magnetic entropy vanishes continuously at B c and the system changes smoothly to a field-polarized paramagnet.