ISING SPIN-GLASS IN A TRANSVERSE MAGNETIC-FIELD

We study the three-dimensional quantum Ising spin glass in a transvers e magnetic field following the evolution of the bond probability distr ibution under renormalization-group transformations. The phase diagram (critical temperature T(c) vs transverse field GAMMA) we obtain shows a finite slope near T = 0, in contrast with the infinite slope for th e pure case. Our results compare very well with the experimental data recently obtained for the dipolar Ising spin glass LiHo0.167Y0.833F4, in a transverse field. This indicates that this system is more appropr iately described by a model with short-range interactions than by an e quivalent Sherrington-Kirkpatrick model in a transverse field.