Alladi Ramakrishnan Hall

Square lattice antiferromagnet: extended degeneracy and the role of fluctuations

Gautam Nambiar

IISc, Bangalore (currently summer student at IMSc)

We study the square lattice antiferromagnet with J1, J2 and J3 interactions. At a special line in parameter space with J2= J1 / 2 and J3 <0, we show that the ground state has an extended degeneracy. We interpret this degeneracy in terms of coexisting spirals. We show how spin wave fluctuations break this degeneracy and select specific states.