The Pseudo-Spin Method in Magnetism and Ferroelectricity International Series of Monographs in Natural Philosophy

The Pseudo-Spin Method in Magnetism and Ferroelectricity deals with the pseudo-spin method in magnetism and ferroelectricity, with emphasis on three important ordered systems: ferromagnets, antiferromagnets, and hydrogen-bonded ferroelectrics. Each system is analyzed in three important temperature regions: low temperatures, the critical region, and high temperatures. The presented mathematical method is predominantly analytical in the sense that all crucial physical quantities are expressed in terms of temperature or the reciprocal lattice vectors. Comprised of four chapters, this volume begins with an introduction to Basic concepts in lattice dynamics, touching on topics such as symmetry groups, light scattering, and the spectrum of ionic crystals. The discussion then turns to phase transitions and covers magnetism, ferroelectricity, and the Ising model with a transverse field. Magnetic elementary excitations are then considered, paying particular attention to the second quantization method; the exchange interaction; the Heisenberg ferromagnet in a boson representation; and high-temperature static susceptibility. The final chapter is devoted to the Green functions and their perturbation expansion; ferromagnetism at low temperatures; antiferromagnetism and ferroelectric modes; and high-temperature dielectric susceptibilities. This book will be of interest to physicists as well as students and researchers in physics.