Disorder-enhanced delocalization and local-moment quenching in a disordered antiferromagnet

Дата и время публикации : 1998-03-09T14:18:08Z

Авторы публикации и институты :
Avinash Singh
Martin Ulmke
Dieter Vollhardt

Ссылка на журнал-издание: Phys. Rev. B vol 58, 8683 (1998)
Коментарии к cтатье: 12 pages, includes 8 postscript figures. To appear in Physical Review B. References added
Первичная категория: cond-mat.str-el

Все категории : cond-mat.str-el, cond-mat.dis-nn

Краткий обзор статьи: The interplay of disorder and spin-fluctuation effects in a disordered antiferromagnet is studied. In the weak-disorder regime (W le U), while the energy gap decreases rapidly with disorder, the sublattice magnetization, including quantum corrections, is found to remain essentially unchanged in the strong correlation limit. Magnon energies and Neel temperature are enhanced by disorder in this limit. A single paradigm of disorder-enhanced delocalization qualitatively accounts for all these weak disorder effects. Vertex corrections and magnon damping, which appear only at order (W/U)^4, are also studied. With increasing disorder a crossover is found at W sim U, characterized by a rapid decrease in sublattice magnetization due to quenching of local moments, and formation of spin vacancies. The latter suggests a spin-dilution behavior, which is indeed observed in softened magnon modes, lowering of Neel temperature, and enhanced transverse spin fluctuations.

Category: Physics