Chiranjeeb Buragohain

The study of low dimensional antiferromagnetic systems in recent times has led to major advances in our understanding about states of strongly correlated electron systems. The low dimensionality allows one to use a plethora of quantum field theoretical methods in analyzing these systems and it is possible to make detailed comparisons between theory and experiment. In this report we concentrate on the dynamical properties of one and two dimensional antiferromagnets. In one dimension, we show that it is possible to understand the dynamics of both integer and half-integer spin antiferromagnets under a unified formalism. We also study an exactly solvable toy model of spin transport to enhance our understanding of spin transport in finite sized systems. Predictions for various experimentally relevant quantities like neutron scattering cross-section are made. In two dimensions we study the problem of a spin impurity embedded in a two dimensional antiferromagnet. We show that the dynamics of the spin is sensitively coupled to the bulk antiferromagnet and carry out a renormalization group analysis of the system. We also derive various critical exponents for the impurity spin dynamics and magnetization.