Spin liquid phase for the frustrated Quantum Heisenberg Antiferromagnet on a square lattice

The existance of a spin disordered ground state for the frustrated Quantum Heisenberg Antiferromagnet on a square lattice is reconsidered. It is argued that there is a unique action which is continuous through the whole phase diagram, except at the Lifshitz point, so that the Neel and helicoidal states can not coexist and there has to be an intermediate spin liquid state. To show it, a detailed study combining Spin-Wave theory, Schwinger Bosons Mean Field Theory and a scaling analysis of the appropriate hydrodynamic action is performed. When done carefully, all these theories agree and strongly support the existance of the spin liquThe manuscript has eight figures, which are available upon request to the author. e-mail address is [email protected]: 21 page