Quantum vector spin-glass models in an applied field

We use the static approximation to investigate the phase diagram of the infinite-ranged quantum Heisenberg spin glass (QHSG) in an external field, as well as the phase diagram of a two-component quantum spin glass (QXYSG) in a transverse or a longitudinal field. For the QHSG we find that, for strong field (H) and low temperature (T), the phase transition into the spin-glass phase characterized by nonzero transverse spin-glass ordering is given by Tcexp[-H2/(2J2S2)], as compared with Tcexp{-H2/[2J2S(S+1)]} for classical spins of magnitude S(S+1). In the case of QXYSG in a transverse field (), the phase boundary terminates at /J=2 for T=0.