On the Atomic Limit of the s–f Model

Abstract

The atomic limit of the s-f model for a system in an external magnetic field is studied. By direct calculation of traces expressions are obtained for the first time for the partition function, average number of electrons, chemical potential, magnetization, susceptibility, mean energy, and specific heat a t arbitrary values of electron concentration, spin, temperature, magnetic field, and exchange and Coulomb interaction parameters. It is shown that the system behaving itself in many respects as an ensemble of "quasi-particles" of four types, i s . holes, down-units, up-units, and pairs is always paramagnetic and the susceptibility may obey both, Curie law and Curie-Weiss law. At subnormally small intra-atomic interactions Schottky anomalies may be observed in the system. HccneAosaHa a a~a s a aToMHoro npeqena s-f MoAem