Structural phase transitions related to magnetic phenomena in CuCrSe2and AgCrSe2magneto-elastics

Introduction to Phase Transitions and Critical Phenomena

Phase Transitions and Collective Phenomena

Structural phase transitions

Structural phase transitions can be studied by a variety of techniques; macroscopic fields, X-ray, light and neutron diffraction, and resonance methods. The information which can be obtained by these different techniques about the order parameter and susceptibility at structural phase transitions is described and compared. Landau theory coupled with the 'sot~ mode' concept provides a simple pic...

Phase Transitions Related to the Pigeonhole Principle

Since Jeff Paris introduced them in the late seventies [Par78], densities turned out to be useful for studying independence results. Motivated by their simplicity and surprising strength we investigate the combinatorial complexity of two such densities which are strongly related to the pigeonhole principle. The aim is to miniaturise Ramsey’s Theorem for 1-tuples. The first principle uses an unl...

Theory of Magnetic Phase Transitions

The existence of magnetic order (also termed collective magnetism) that is the orderly arrangement of the magnetic spins appearing in materials below an ordering temperature (e.g., the Curie temperature, TC, of a ferromagnet or the Neel temperature, TN, of an antiferromagnet; see Magnetic Moment and Magnetization) points to a class of physical phenomena that can be described as magnetic phase t...