(South African Institute of Physics, 2014) Muchono, Blessed; Sheppard, C.J; Prinsloo, A.R.E.; Alberts, H.L.
The magnetic susceptibility as a function of temperature, 𝜒𝜒(𝑇𝑇), on a spin-densitywave
antiferromagnetic (Cr98.4Al1.6)100-xMox alloy system in the concentration range 0 ≤ x ≤ 8.8
is reported in order to investigate the possibility of quantum critical behaviour in this alloy
system. Néel temperatures, TN, obtained from 𝜒𝜒(𝑇𝑇) measurements decrease with Mo
concentration and sharply tend towards 0 K at a critical concentration xc ≈ 4.5.
Antiferromagnetism is suppressed to below 4 K in alloys with x ≳ 4.5. Alloys in the
concentration range 0 ≤ x ≤ 3.0 depict an upturn in the 𝜒𝜒(𝑇𝑇) curves just above the Néel
temperature. The upturn is attributed to local magnetic moments formed around the impurity
atoms. The magnetic phase diagram of the alloy system points towards the existence of a
quantum critical point at the critical concentration x = xc. The suggestion of quantum critical
behaviour in this alloy system from previous electrical resistivity(𝜌𝜌), Seebeck coefficient (𝑆𝑆)
and specific heat (𝐶𝐶p) measurements is corroborated in this study.