Orientation-dependent Surface Research Articles

Pressure dependence of the de Haas-van Alphen effect in potassium

The pressure dependence of the de Haas-van Alphen effect in potassium has been studied up to 4.6 kbar. The measured dHvA frequencies were lower than the free-electron scaling predictions for all pressures. The low pressure area compressibility of the Fermi surface was found to be 15% lower than the free-electron value. The results show the failure of the free-electron theory for potassium. The decrease in both the Fermi surface cross sections and the area compressibilities indicate the possible existence of a new ground state energy as predicted by the charge-density wave model. The observed orientation dependent Fermi surface distortions with pressure and the presence of beats in the dHvA oscillations are in qualitative agreement with the charge-density wave model.

Temperature and orientation dependent surface critical current in superconducting niobium single crystals

A pronounced anisotropy is observed in the surface critical current of Nb single crystals at low temperature. It is believed to be related to the anisotropy in K.