Criticality and Quenched Disorder: Harris Criterion Versus Rare Regions

Autor(es)

Vojta, Thomas ^[1] ; Hoyos, Jose A. ^[2]

Afiliação do(s) autor(es)

^[1] Missouri Univ Sci & Technol, Dept Phys, Rolla, MO 65409 - USA

^[2] Univ Sao Paulo, Inst Fis Sao Carlos, BR-13560970 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Physical Review Letters; v. 112, n. 7 FEB 20 2014.
• Citações Web of Science: 23

Resumo

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. (AU)

• Processo FAPESP: 13/09850-7 - Disorder, Dynamics, Frustration and Topology in Quantum Condensed Matter
• Beneficiário: José Abel Hoyos Neto
• Modalidade de apoio: Auxílio à Pesquisa - Reunião - Exterior