Abstract
The magnetic material in a transverse magnetic field 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 -induced magnetization along the direction, combined with the local random dilution-induced destruction of crystalline symmetries, generates, via the predominant dipolar interactions between ions, random fields along the Ising direction. This identifies in 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 and render the -induced quantum criticality in likely inaccessible.
- Received 6 September 2006
DOI:https://doi.org/10.1103/PhysRevLett.97.237203
©2006 American Physical Society