Fermi Surface of Electrons and Holes in C₈K: First-Principles Study

Abstract

The band structure and Fermi surface of C₈K are studied by the first-principles calculation using two different types of basis sets to resolve the disagreements in the results of both experimental and theoretical studies. It is concluded that C₈K is a compensated metal with the same number of holes and electrons. The Fermi surface of C₈K is composed of the hole cylinders and electron prisms. The hole cylinders originated from the state in which the graphite interlayer state, π state, and potassium 4s state are hybridized have the simply connected topology. On the other hand, the topology of the electron prisms originated from the π state is multiply connected with the electron tube. Furthermore, we calculate the cross sections of these Fermi surfaces and compare them with the dHvA frequencies. The observed two dHvA frequencies can be assigned to the maximum and minimum cross sections of the electron prisms. We also predict that four dHvA frequencies originated from the hole cylinders should be observed.

Key Words:

• graphite intercalation compound
• potassium
• Fermi surface
• interlayer state
• first-principles calculation