Theory of the Open-Orbit Magnetoresistance of Potassium

The discovery of open-orbit magnetoresistance peaks in potassium shows that its Fermi surface is multiply connected. A charge-density-wave structure (which would have 24 domain orientations and five open-orbit directions per domain) explains the main features. The magnetic field at which open-orbit peaks appear depends on domain size, which we find to be {~}0.1 mm.