Impurity Heat Capacity and its Relation to Entanglement in Dilute Magnetic Alloys

Abstract

Using an asymptotic solution of the thermodynamics of a dilute s-d system comprising M magnetic impurities interacting with the electron gas, the impurity energy and impurity heat capacity ΔC(T) are derived for dilute magnetic alloys with spin 1/2 and spin 3/2 impurities. ΔC(T) can be viewed as a measure of entanglement between impurities and electrons in a dilute magnetic alloy. The parameters which enter ΔC are adjusted to fit experimental data on impurity heat capacity of CuCr and ( La 1−x Ce x) Al 2. Agreement is satisfactory for CuCr , at temperatures below 1K, and good for ( La 1−x Ce x) Al 2. The magnitude of theoretical ΔC(T) agrees with experiment and does not require scaling as in previous s-d theories. Nonlinear dependence of ΔC(T) on impurity concentration has been accounted for the first time.