In:
Journal of Applied Physics, AIP Publishing, Vol. 50, No. B11 ( 1979-11-01), p. 7373-7373
Abstract:
There exists in the literature a large number of experiments involving the basic characteristics of spin-glass materials. Much less information is available on order parameters and critical properties of spin-glass. The present work is motivated by a desire to study these properties and is concerned with the low-dc-field susceptibility of CuMn spin-glass containing 1.08 and 2.02 at. %Mn, using a superconducting quantum-interference device (SQUID). The zero-field cooled initial susceptibility shows a cusplike peak at Tg, the transition temperature to a spin-glass state. After field cooling from T≳Tg (even for H=2 Oe), the susceptibility below Tg is nearly independent of temperature with the constant value of ∼0.97χ (Tg). The high temperature susceptibility follows a Curie-Weiss law until just above Tg; the value of the Weiss constant is very small. Sherrington and Kirkpatrick obtained a spin-glass solution characterized by the Edwards-Anderson type order parameter q(T). The susceptibility χ provides an experimental probe of q(T), since χ (T) ={C(T)[1−q(T)]}×{T−ϑ (T)[1−q(T)] }−1. In the mean-field theory, C(T) and ϑ (T) are constants, corresponding to the Curie constant and Weiss constant, respectively. Using this theory, the order parameter q(T) as a function of temperature is extracted from the susceptibility data. A critical index β?1 is obtained assuming a power law for q(T) ∝ (1−T/Tg)3. The value of β is in agreement with the prediction of the mean-field theory: β=1. It appears however to exclude the renormalization-group method prediction, obtained by Harris et al. They derived expansions for the exponents in power of ε=6−d, d is the dimension of the system, which leads in first order of ε to β=2.5 for the Ising model, 1.75 for the X-Y model and 1.6 for the Heisenberg model. It also excludes the prediction of the percolation theory by Kirkpatrick, which gives β=0.39.
Type of Medium:
Online Resource
ISSN:
0021-8979
,
1089-7550
Language:
English
Publisher:
AIP Publishing
Publication Date:
1979
detail.hit.zdb_id:
220641-9
detail.hit.zdb_id:
3112-4
detail.hit.zdb_id:
1476463-5
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