Magnetic Susceptibility of Dilute Al-Mn Alloys

Abstract

The temperature dependence of the magnetic susceptibility of pure aluminum and three aluminum alloys containing 0.045, 0.21, and 0.35 at.% manganese has been measured between 2 and 300 °K. All of the susceptibility results can be fitted to an equation of the form $A+B{T}^2$. The experimental values of the coefficients $A$ and $B$ for pure aluminum are 19.2 ± 0.1 × ${10}^{-7\mathrm{}}$ emu/cc and 3.7 ± 0.1 × ${10}^{-12\mathrm{}}$ emu/cc/(°${\mathrm{K}}^2$), which are in good agreement with theoretical values derived from the known band structure of aluminum. An additional susceptibility component is observed in th Al-Mn alloys, and the experimental results can be characterized by the equation $\frac{\Delta K_{\mathrm{Mn}}\mathrm{}\left(T\right)\mathrm{}}{C}$ emu/cc at.% $\mathrm{Mn}=13.8\mathrm{}\pm 0.8\times {10}^{-7\mathrm{}}-(14\mathrm{}\pm 3\times {10}^{-13\mathrm{}})T^2$. The experimentally determined coefficients can be explained by considering an exchange enhancement of the Pauli paramagnetism within the framework of a Hartree-Fock approximation. Values of the exchange enhancement factor $\eta$, and the width of the virtual bound $d$ states, $\Delta$, can be uniquiely determined and have the values 4.4 ± 1 and 0.33 ± 0.05 eV, respectively.