Issue
EPL
Volume 87, Number 2, July 2009
Article Number 27003
Number of page(s) 5
Section Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties
DOI http://dx.doi.org/10.1209/0295-5075/87/27003
Published online 29 July 2009
EPL, 87 (2009) 27003
DOI: 10.1209/0295-5075/87/27003

Valence-bond theory of highly disordered quantum antiferromagnets

S. Zhou1, J. A. Hoyos2, V. Dobrosavljević1 and E. Miranda3

1   National High Magnetic Field Laboratory, Florida State University - Tallahassee, FL 32310, USA
2   Department of Physics, Duke University - Durham, NC 27708, USA
3   Instituto de Física Gleb Wataghin, Unicamp - C.P. 6165, Campinas, São Paulo 13083-970, Brazil

jh146@phy.duke.edu

received 16 April 2009; accepted in final form 1 July 2009; published July 2009
published online 29 July 2009

Abstract
We present a large-N variational approach to describe the magnetism of insulating doped semiconductors based on a disorder-generalization of the resonating-valence-bond theory for quantum antiferromagnets. This method captures all the qualitative and even quantitative predictions of the strong-disorder renormalization group approach over the entire experimentally relevant temperature range. Finally, by mapping the problem on a hard-sphere fluid, we could provide an essentially exact analytic solution without any adjustable parameters.

PACS
75.10.Jm - Quantized spin models.
71.55.-i - Impurity and defect levels.
71.70.Gm - Exchange interactions.

© EPLA 2009