Large N expansion for frustrated and doped quantum antiferromagnets

  title={Large N expansion for frustrated and doped quantum antiferromagnets},
  author={Subir Sachdev and Nicholas Read},
A large N expansion technique, based on symplectic (Sp(N)) symmetry, for frustrated magnetic systems is studied. The phase diagram of a square lattice, spin S, quantum antiferromagnet with first, second and third neighbor antiferromagnetic coupling (the J1-J2-J3 model) is determined in the large-N limit and consequences of fluctuations at finite N for the quantum disordered phases are discussed. In addition to phases with long range magnetic order, two classes of disordered phases are found: (i… CONTINUE READING