Abstract
Abstract
We show that equilibrium systems in d dimension that obey the inequality
d
ν
>
2
,
known as Harris criterion, exhibit suppressed energy fluctuation in their critical state. Ashkin–Teller model is an example in d = 2 where the correlation length exponent ν varies continuously with the inter-spin interaction strength λ and exceeds the value
d
2
set by Harris criterion when λ is negative; there, the variance of the subsystem energy across a length scale l varies as
l
d
−
α
with hyperuniformity exponent
α
=
2
(
1
−
ν
−
1
)
.
Point configurations constructed by assigning unity to the sites which has coarse-grained energy beyond a threshold value also exhibit suppressed number fluctuation and hyperuniformiyty with same exponent
α
.