Criticality and quenched disorder: Harris criterion versus rare regions.
Phys Rev Lett
; 112(7): 075702, 2014 Feb 21.
Article
en En
| MEDLINE
| ID: mdl-24579616
ABSTRACT
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 exponent z' diverges upon approaching the transition, suggesting unconventional critical behavior. In contrast, if the Harris criterion is fulfilled, power-law Griffiths singularities can coexist with clean critical behavior, but z' saturates at a finite value. We present applications of our theory to a variety of systems including quantum spin chains, classical reaction-diffusion systems and metallic magnets, and we discuss modifications for transitions above the upper critical dimension. Based on these results we propose a unified classification of phase transitions in disordered systems.
Buscar en Google
Banco de datos:
MEDLINE
Asunto principal:
Teoría Cuántica
/
Transición de Fase
/
Modelos Teóricos
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
Phys Rev Lett
Año:
2014
Tipo del documento:
Article
País de afiliación:
Estados Unidos