Hyperfine Fields and Electronic Structure of CsCl-Type Ternary Alloys of the First Transition Series

Abstract

The ${}_{}{}^{59}{}_{}{}^{}\mathrm{Co}$ Knight shift $K$ and the ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ isomer shift have been measured in $\mathrm{Ti}{\mathrm{Fe}}_{1-x}{\mathrm{Co}}_x$ alloys over most of the composition range $0\le x\le 1$. The experimental results are discussed in terms of correlations with electron concentration and $s$ admixture in the $d$ bands. At room temperature, $K$ varies from a maximum of (3.2±0.2)% at $x\approx 0.8$, and roughly follows the electronic specific heat as the composition is varied, with a minimum of $K=(0.8\mathrm{}\pm 0.2)\%$ near $x=0\mathrm{}$. $K$ increases substantially as the temperature is lowered for $x$ near 1, and decreases somewhat for $x$ near 0. The maximum $K$ measured is (4.7±0.2)% for $x\approx 0.8$ at 120°K. The slopes of $K$ versus susceptibility vary from $+86\mathrm{} \frac{\mathrm{kG}}{{\mu }_B}$ per formula unit for $x=0.8\mathrm{}$ to $-47\mathrm{} \frac{\mathrm{kG}}{{\mu }_B}$ per formula unit for $x=0.05\mathrm{}$. The isomer-shift variation, from -0.15±0.01 (mm/sec relative to pure Fe) at TiFe to -0.19±0.02 at TiCo, is similar to that of Fe in Cr-Mn. The ${}_{}{}^{47,49}{}_{}{}^{}\mathrm{Ti}$ Knight shift in TiFe is (0.26±0.04)% at room and at liquid-nitrogen temperatures.