Effect of Pressure and Magnetic Field on the Connectivity of the Fermi Surface of Zinc

We report quantitative measurements of the pressure dependence (to {~}6 kbar) of the lengths of the one-dimensional angular regions of applied field producing open orbits in the basal plane in Zn (δ₁ and δ₃ whiskers). We find that both whiskers increase in length with pressure with the following slopes: dδ₁dP=0.100±0.015 deg/kbar, dδ₂dP=0.07±0.01 deg/kbar. Our results indicate that the connectivity in the basal plane is enhanced by hydrostatic pressure, as is expected from nearly-free-electron considerations. A system for obtaining 4π-steradian magnetic field scan of a stationary sample at 4^∘{}K is described. Qualitative measurements of the effect of high magnetic field ({~}60 kOe) on the length of these whiskers showed that the length of δ₃ was not affected but that a small increase in the length of δ₁ could be detected with increasing field. The effect of pressure (to {~}5 kbar) on the period of the oscillations in the magnetoresistance associated with the minimum cross section of the needles is found to agree with the very-low-pressure He-gas work but not with work in the ice bomb or in frozen kerosene-oil mixtures. Consideration of all these results leads to a new zero-pressure assignment for the relation between Fermi-surface dimensions and the angular lengths of the whiskers. Using this assignment the following pressure derivatives of the radius r of the monster, the height hN, of magnetic breakdown on the needles, and the height hW of the waists of the monster are calculated: dlnr/dP=-0.0009/kbar, dlnhNdP=-0.007/kbar and dlnhWdP=0.015/kbar. The results of our pressure measurements on Zn are consistently different from those obtained in solid pressure-transmitting media other than He. A comparison is made of the various results in the literature on the pressure dependence of the period of the oscillatory component of transport phenomena in Zn for H∥[0001], which we feel demonstrates the superiority of the solid-He technique for low-temperature pressure generation in the range 0-9 kbar.