Master's Defense: Oliver Ovsée Laub Solow

Effective bond theory for frustrated magnets

In this thesis, we study classical frustrated magnets through the use of a field-theoretical approach known as Nematic Bond Theory. In the field-theoretical language of this approach, we can derive a simple set of equations by neglecting the vertex corrections, which we show is a valid approximation in certain regimes. We apply this framework to the honeycomb lattice with up to third-nearest neighbor couplings, and find that the relation between the coupling strengths and the nematic transition temperature is different for different phase boundaries. We then study the triangular lattice with RKKY interactions. We find that depending on the parameters of the interaction, this system can exhibit a number of different phases. Near phase boundaries, we find complex behaviors like spin liquids, and an as of yet unexplained jump in the critical temperature.