22 research outputs found
Ground state numerical study of the three-dimensional random field Ising model
The random field Ising model in three dimensions with Gaussian random fields
is studied at zero temperature for system sizes up to 60^3. For each
realization of the normalized random fields, the strength of the random field,
Delta and a uniform external, H is adjusted to find the finite-size critical
point. The finite-size critical point is identified as the point in the H-Delta
plane where three degenerate ground states have the largest discontinuities in
the magnetization. The discontinuities in the magnetization and bond energy
between these ground states are used to calculate the magnetization and
specific heat critical exponents and both exponents are found to be near zero.Comment: 10 pages, 6 figures; new references and small changes to tex
Ordering in the dilute weakly-anisotropic antiferromagnet Mn(0.35)Zn(0.65)F2
The highly diluted antiferromagnet Mn(0.35)Zn(0.65)F2 has been investigated
by neutron scattering in zero field. The Bragg peaks observed below the Neel
temperature TN (approximately 10.9 K) indicate stable antiferromagnetic
long-range ordering at low temperature. The critical behavior is governed by
random-exchange Ising model critical exponents (nu approximately 0.69 and gamma
approximately 1.31), as reported for Mn(x)Zn(1-x)F2 with higher x and for the
isostructural compound Fe(x)Zn(1-x)F2. However, in addition to the Bragg peaks,
unusual scattering behavior appears for |q|>0 below a glassy temperature Tg
approximately 7.0 K. The glassy region T<Tg corresponds to that of noticeable
frequency dependence in earlier zero-field ac susceptibility measurements on
this sample. These results indicate that long-range order coexists with
short-range nonequilibrium clusters in this highly diluted magnet.Comment: 7 pages, 5 figure
Physicochemical properties and antioxidant activities of melanin and fractions from Auricularia auricula fruiting bodies
Exposing the spin-glass ground state of the nonsuperconducting La<sub>2-x</sub>Sr<sub>x</sub>Cu<sub>1-y</sub>Zn<sub>y</sub>O<sub>4</sub> high-T<sub>c</sub> oxide
We have studied the spin glass behaviour of non-superconducting
LaSrCuZnO (). As in the
superconducting analogues of these samples the spin glass transition
temperature decreases with increasing , and vanishes at . A
local enhancement in at is also observed and attributed to
stripe ordering. The disappearance of for is discussed in
terms of a quantum phase transition.Comment: Text, 4 figure
Unveiling the Mechanisms of Aquaglyceroporin‐3 Water and Glycerol Permeation by Metadynamics
Water and glycerol permeation via human AQP3 are described exploiting advanced metadynamics approaches, which enabled to both explore the free energies involved in pore permeation, as well as to achieve a description of the mechanisms with an atomistic level of detail. Moreover, thanks to this technique, a basic water transport mechanism, single‐filed and bidirectional in nature was retrieved, on which glycerol molecules are inserted during channel permeation. Therein, activation energies result from static and dynamic effects involving hydrogen bonds within the water filament and among substrate molecules and pore internal residues