Pressure Dependence of the Knight Shift in Pt

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°, 0°, and -78.0°C. $\mathrm{}\left|K\right|\mathrm{}$ 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 $K\left(T\right)\mathrm{}$ at constant pressure and the present pressure-dependence data, may be written as $K=K_0+B{T}^2+O\left[{\left(\frac{T}{T_d}\right)}^4\right]$, 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.