Volume 88, Number 6, December 2009
Article Number 66002
Number of page(s) 5
Section Condensed Matter: Structural, Mechanical and Thermal Properties
Published online 01 December 2009
EPL, 88 (2009) 66002
DOI: 10.1209/0295-5075/88/66002

Correlated random fields in dielectric and spin glasses

M. Schechter1, 2 and P. C. E. Stamp1, 3

1   Department of Physics and Astronomy, University of British Columbia - Vancouver, B.C., Canada V6T 1Z1
2   Department of Physics, Ben Gurion University - Beer Sheva 84105, Israel
3   Pacific Institute for Theoretical Physics, University of British Columbia - Vancouver, B.C., Canada V6T 1Z1

received 6 October 2009; accepted in final form 23 November 2009; published December 2009
published online 22 December 2009

Both orientational glasses and dipolar glasses possess an intrinsic random field, coming from the volume difference between impurity and host ions. We show this suppresses the glass transition, causing instead a crossover to the low-T phase. Moreover the random field is correlated with the inter-impurity interactions, and has a broad distribution. This leads to a peculiar variant of the Imry-Ma mechanism, with “domains” of impurities oriented by a few frozen pairs. These domains are small: predictions of domain size are given for specific systems, and their possible experimental verification is outlined. In magnetic glasses in zero field the glass transition survives, because the random fields are disallowed by time-reversal symmetry; applying a magnetic field then generates random fields, and suppresses the spin glass transition.

PACS - Nonmetallic glasses (silicates, oxides, selenides, etc.).
75.10.Nr - Spin-glass and other random models.
75.10.Jm - Quantized spin models.

© EPLA 2009