LAUSR

Abstract Indications of quantum critical behaviour (QCB), driven by electron-hole pair breaking effects through Mo doping of Cr98.4Al1.6 are reported. Previous studies on the electrical resistivity ( ρ ) , Seebeck coefficient ( S ) , Sommerfeld electronic specific heat coefficient ( γ ) and magnetic susceptibility ( χ ) as a function of temperature on the (Cr98.4Al1.6)100-yMoy alloy system point towards the existence of a quantum critical point (QCP) at y c ≈ 4.5. In the present study the Hall coefficient R H measurements and an analysis of the previous results are used to substantiate the presence of a QCP in the alloy system. The charge carrier density at 2 K, ( q R H ( 2 K ) ) − 1 , of the alloy systems increases continuously with y from the antiferromagnetic (AFM) phase through y c ≈ 4.5 and into the paramagnetic (P) phase. Scaling relationships between the magnetic contribution to the electrical resistivity, Δ ρ 2 K , the magnetic contribution to the Sommerfeld electronic specific heat coefficient, Δ γ , and ( q R H ( 2 K ) ) − 1 , are furthermore used to support the presence of a QCP in the alloy system. d S / d T in the temperature limit T → 2 K depicts an anomalous behaviour in the form of an upturn on decreasing y through the QCP, y c ≈ 4.5. The critical exponents in the vicinity of the QCP were found to be β  = 0.5 ± 0.1 for the Δ ρ 2 K / ρ 2 K ( y ) curve and γ  = 0.4 ± 0.1 for the T N ( y ) curve. The nature of the QCP in the present alloy system is classified as an incommensurate (I) spin-density-wave (SDW) type, driven mainly by electron-hole pair breaking effects.