Ising model in a transverse field. I. Basic theory

Content Provider	Scilit
Author	Stinchcombe, R. B.
Copyright Year	1973
Description	Journal: Journal of Physics C: Solid State Physics A brief review is first made of systems for which the spin-1/2 Ising model in a transverse field provides a useful description (insulating magnetic systems, order-disorder ferroelectrics, cooperative Jahn-Teller systems and other systems with 'pseudo-spin'- phonon interactions). A perturbation expansion is then developed which provides for all temperatures an approximate description of the model. The perturbation series is classified with respect to the small parameter 1/z, where z is the number of psins interacting with a given spin; this generates the molecular-field approximation and the random-phase approximation as the lowest-order description of the thermodynamic functions and correlation functions respectively. The leading-order approximations for the correlation functions, susceptibilities and spectral functions are discussed in detail. The formalism, which is the first application of such techniques to systems with varying magnetization direction, provides a basis for subsequent higher-order calculations of the free energy and correlation functions.
Related Links	http://iopscience.iop.org/article/10.1088/0022-3719/6/15/009/pdf
Ending Page	2483
Page Count	25
Starting Page	2459
ISSN	00223719
DOI	10.1088/0022-3719/6/15/009
Journal	Journal of Physics C: Solid State Physics
Issue Number	15
Volume Number	6
Language	English
Publisher	IOP Publishing
Publisher Date	1973-08-06
Access Restriction	Open
Subject Keyword	Journal: Journal of Physics C: Solid State Physics Condensed Matter Physics Random Phase Approximation Correlation Function
Content Type	Text
Resource Type	Article
Subject	Physics and Astronomy Condensed Matter Physics Engineering