Numerical Simulations of Spin Glasses: Methods and Some Recent Results

I. Morgenstern

Hajime Takayama, Petra E. Jönsson

The aging phenomena in Ising spin glasses in a magnetic field are investigated both by the numerical simulation on three-dimensional Ising Edwards-Anderson model and by the experiment on the Fe0.55Mn0.45TiO3 Ising spin glass. After reviewing our recent numerical work on the field-shift aging protocol, by which we argue that the spin-glass (SG) phase is unstable in a static magnetic field of any strength, we present the nonequilibrium aspects of the field-cooled magnetization in a relatively small field observed numerically and experimentally. The results are compatible with the absence of the equilibrium SG phase in a field.

Ilaria Paga, J. P. He, Marco Baity‐Jesi +23 more

Rejuvenation and memory, long considered the distinguishing features of spin glasses, have recently been proven to result from the growth of multiple length scales. This insight, enabled by simulations on the Janus II supercomputer, has opened the door to a quantitative analysis. We combine numerical simulations with comparable experiments to introduce two coefficients that quantify memory. A third coefficient has been recently presented by Freedberg et al. We show that these coefficients are physically equivalent by studying their temperature and waiting-time dependence.

R. N. Bhatt, A. P. Young

Alain H. Billoire

Ian A. Campbell, L. de Arcangelis

Through “damage spreading” numerical simulations, we study the Ising spin glass in three dimensions with ± J near-neighbour interactions. The results are compared to other simulation data; we conclude that the damage spreading method can provide good estimates of the transition temperatures in this type of system. A discussion is given of phase transitions in spin glasses in terms of the geometry of phase space.