Valence-bond theory of highly disordered quantum antiferromagnetsS. 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
received 16 April 2009; accepted in final form 1 July 2009; published July 2009
published online 29 July 2009
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.
75.10.Jm - Quantized spin models.
71.55.-i - Impurity and defect levels.
71.70.Gm - Exchange interactions.
© EPLA 2009