Induced random fields in the LiHoxY1-xF4 quantum ising magnet in a transverse magnetic field

The LiHoxY1-xF4 magnetic material in a transverse magnetic field B(x)x boolean AND perpendicular to the Ising spin direction has long been used to study tunable quantum phase transitions in a random disordered system. We show that the B-x-induced magnetization along the x boolean AND direction, combined with the local random dilution-induced destruction of crystalline symmetries, generates, via the predominant dipolar interactions between Ho3+ ions, random fields along the Ising z boolean AND direction. This identifies LiHoxY1-xF4 in B-x as a new random field Ising system. The random fields explain the rapid decrease of the critical temperature in the diluted ferromagnetic regime and the smearing of the nonlinear susceptibility at the spin-glass transition with increasing B-x and render the B-x-induced quantum criticality in LiHoxY1-xF4 likely inaccessible.