Canadian Journal of Physics
Magnetization plateaux and bound states of the Shastry–Sutherland model for SrCu2(BO3)2
Tsutomu Momoi, Kiyohito Totsuka
Abstract
In this paper, we briefly review our recent studies of the Heisenberg anti-ferromagnet on the ShastrySutherland lattice for SrCu2(BO3)2 under magnetic fields. Treating magnetic excitations promoted by the field as Bose particles and using a strong-coupling expansion, we derived an effective Hamiltonian for the magnetic particles. Anisotropic repulsive interactions between particles induce "insulating" states with a stripe spin-density wave structure at magnetization m/msat = 1/3 and with a checkerboard structure at 1/2, and thereby form magnetization plateaux. We also demonstrated how the unique geometry of the ShastrySutherland lattice affects dynamical properties and makes a novel type of quintuplet (S = 2) bound states condense for very small magnetization. PACS Nos.: 75.50-y, 75.60Ej, 75.10Jm