Magnetism in Strongly Correlated Systems

This book presents analytic and numerical studies of§magnetism in strongly correlated solid-state systems.§Competing tendencies in these systems can lead to§spontaneous nanoscale structures, such as stripes and§checkerboards. There are three topics explored in§this book. First, spin waves and magnetic excitations§for well-ordered spin structures are studied by using§a suitably parametrized Heisenberg§model. Both site-centered and bond-centered antiphase§domain walls are considered for a range of spacings§between stripes and checkerboard antiphase domain§walls. Second, quasi-two-dimensional spin systems are§explored by using the Stochastic Series Expansion§Quantum Monte Carlo method. The order-disorder phase§transitions are studied for both static and dynamic§bond-diluted Heisenberg spin systems. Varying the§interlayer coupling, the Neel temperature and§universal scalings are studied for weakly coupled§Heisenberg antiferromagnetic layers consisting of§coupled ladders. Third, a two-dimensional Heisenberg§antiferromagnet with nearest-neighbor and four-spin§ring exchange is studied, which exhibits a quantum§phase transition from the Valence Bond Solid phase to§Neel order.