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RR Singh

Publications and source records attributed to RR Singh.

At least 19 recordsLinked to original sources
PubMed2000

Strong-coupling expansions for multiparticle excitations: continuum and bound states

We present a new linked cluster expansion for calculating properties of multiparticle excitation spectra to high orders. We use it to obtain the two-particle spectra for systems of coupled spin-half dimers. We find that even for weakly coupled dimers the spectrum is very rich, consisting of many bound states. The number of bound states depends on both geometry of coupling and frustration. Many of the bound states can only be seen by going to sufficiently high orders in the perturbation theory, showing the extended character of the pair attraction.

Journal Article↗
PubMed2000

Exact demonstration of magnetization plateaus and first-order dimer-Neel phase transitions in a modified shastry-sutherland model for SrCu2(BO3)(2)

We study a generalized Shastry-Sutherland model for the material SrCu2(BO3)(2). Along a line in the parameter space, we show rigorously that the model has a first-order phase transition between dimerized and Neel-ordered ground states. Furthermore, when a magnetic field is applied in the dimerized phase, magnetization plateaus develop at commensurate values of the magnetization. We also discuss various aspects of the phase diagram and properties of this model away from this exactly soluble line, which include gap-closing continuous transitions between dimerized and magnetically ordered phases.

Journal Article↗