Zero-temperature spinglass–ferromagnetic transition: Scaling analysis of the domain-wall energy

Cécile Monthus (1) , Thomas Garel (1)

1 IPHT - Institut de Physique Théorique - UMR CNRS 3681

For the Ising model with Gaussian random coupling of average $J_0$ and unit variance, the zero-temperature spinglass-ferromagnetic transition as a function of the control parameter $J_0$ can be studied via the size-$L$ dependent renormalized coupling defined as the domain-wall energy $J^R(L) \equiv E_{GS}^{(AF)}(L)-E_{GS}^{(F)}(L)$ (i.e. the difference between the ground state energies corresponding to AntiFerromagnetic and and Ferromagnetic boundary conditions in one direction). We study numerically the critical exponents of this zero-temperature transition within the Migdal-Kadanoff approximation as a function of the dimension $d=2,3,4,5,6$. We then compare with the mean-field spherical model. Our main conclusion is that in low dimensions, the critical stiffness exponent $\theta^c$ is clearly bigger than the spin-glass stiffness exponent $\theta^{SG}$, but that they turn out to coincide in high enough dimension and in the mean-field spherical model. We also discuss the finite-size scaling properties of the averaged value and of the width of the distribution of the renormalized couplings.

Domaines: Physique [physics]

Cécile Monthus, Thomas Garel. Zero-temperature spinglass–ferromagnetic transition: Scaling analysis of the domain-wall energy. Biophysical Reviews and Letters, 2014, 89 (18), ⟨10.1103/PhysRevB.89.184408⟩. ⟨cea-01323246⟩