Pressure Dependence of the Knight Shift in Pt

Abstract

The Knight shift $K$ of ${\mathrm{Pt}}^{195}$ in platinum metal was measured as a function of hydrostatic pressure up to about 8000 kg/${\mathrm{cm}}^{2}$, at three temperatures, 64.8\ifmmode^\circ\else\textdegree\fi{}, 0\ifmmode^\circ\else\textdegree\fi{}, and -78.0\ifmmode^\circ\else\textdegree\fi{}C. $|K|$ decreases with increasing pressure. The pressure dependence of $K$ changes markedly with temperature, following a ${T}^{2}$ law. The temperature dependence of $K$ at constant volume, which has been derived from the previously obtained $K(T)$ at constant pressure and the present pressure-dependence data, may be written as $K={K}_{0}+B{T}^{2}+O[{(\frac{T}{{T}_{d}})}^{4}]$, where ${T}_{d}$ is the degeneracy temperature of the $d$-band holes. These observations agree with the model proposed by Clogston et al. The experimental volume dependence of ${K}_{0}$ and $B$ is analyzed using a standard band model. The volume dependences of (i) the Fermi depths of the $s$ and the $d$ band, (ii) the exchange parameter for the $d$ band, and (iii) the number of the $d$ holes are derived from the experimental data.