Interference effects between Berry-phase factors in spin-tunneling systems have been discussed by several groups in the context of quantum magnets. I point out that similar effects appear in the semiclassical analysis of the two-dimensional doped antiferromagnet. As a consequence, the sign of the dispersion of a spin polaron in the t-J model depends on the spin size s in ${\mathit{e}}^{\mathit{i}2\mathrm{\ensuremath{\pi}}\mathit{s}}$. Thus we arrive at a semiclassical interpretation of the… Expand

The interplay of spin and charge degrees of freedom, introduced by doping mobile holes into a Mott insulator with strong antiferromagnetic (AFM) correlations, is at the heart of strongly correlated… Expand

We uncover the low-energy spectrum of a t-J model for electrons on a square lattice of spin-1 iron atoms with 3dxz and 3dyz orbital character by applying Schwinger-boson-slave-fermion mean-field… Expand

A review of quantum coherence effects in mesoscopic spin systems is presented. We begin with a general introduction to the topic of mesoscopic effects in magnetism and give some specific examples of… Expand

The authors discuss concepts used by them and others for studying high temperature superconductivity. These shed some light on basic questions. Suggestions are presented which stimulate thoughtful… Expand