Criticality and Quenched Disorder: Harris Criterion Versus Rare Regions
Criticality and Quenched Disorder: Harris Criterion Versus Rare Regions
We employ scaling arguments and optimal fluctuation theory to establish a general relation between quantum Griffiths singularities and the Harris criterion for quantum phase transitions in disordered systems. If a clean critical point violates the Harris criterion, it is destabilized by weak disorder. At the same time, the Griffiths dynamical …