The magnetic instability of Yb₂Pd₂(In,Sn) in a non-Fermi liquid environment

Abstract

Various concentrations of the solid solution Yb2Pd2In1−xSnx ranging from x = 0 to 1 with the tetragonal Mo2FeB2-type structure were prepared and their physical properties were studied by means of bulk and spectroscopic measurements as a function of temperature, pressure and magnetic fields. Results deduced from these studies indicate a slight variation of the valency of the Yb ions, from for both border compounds to ν = 3 at x = 0.6. This variation gives rise to the appearance of long range magnetic order in a narrow concentration region around x = 0.6, while both border compounds remain non-magnetic. The outstanding concentration dependence for the ordered regime may be indicative of two quantum critical points, a novel feature not yet observed in Yb compounds.

Reentrant quantum criticality in Yb2Pd2Sn

“…Similar features are observed in the resistivity of Yb 2 Pd 2 (In, Sn) for concentrations at which a magnetic phase transition occurs [3]. There, the anomalies at T = T N are weak, but the antiferromagnetic (AFM) transition is clearly indicated by a sharp, λ-like, feature in the specific heat data [3]. AFM order with stable Yb-moments (≈ 1 µ B ) and a propagation vector k = (0, 0, 1/2) is revealed by elastic neutron scattering, too [8].…”

“…Following Fisher et al [7], we assume that the inflexion point of dρ/dT marks a magnetic phase transition. Similar features are observed in the resistivity of Yb 2 Pd 2 (In, Sn) for concentrations at which a magnetic phase transition occurs [3]. There, the anomalies at T = T N are weak, but the antiferromagnetic (AFM) transition is clearly indicated by a sharp, λ-like, feature in the specific heat data [3].…”

“…The pressure dependence of T N and T K mimics the concentration dependence of T N and T K observed in Yb 2 Pd 2 (In, Sn) [3]. For the latter, however, the Grüneisen parameter Ω K = −∂(ln T K )/∂(ln V ) is negative for all concentrations, while in Yb 2 Pd 2 Sn, Ω K < 0 for p 2 GPa and Ω K > 0 for p 2 GPa.…”

“…At ambient pressure, Yb 2 Pd 2 Sn is in a VF state, with Yb valence ν ≈ 2.9 [3]. In such a system, magnetic instabilities are unlikely [4] and the GS is usually of a Fermi liquid (FL) type.…”

Phase relationships at 600°C of the Yb–Pd–Sn system from 25 to 100at.% Yb

“…Yb 2 Pd 2 Sn is another compound of particular interest in the Yb-Pd-Sn system. In fact, possible occurrence of two quantum critical points (QCP) in Yb 2 Pd 2 Sn has been found either by applying pressure [8] than by doping with In [9,10].…”