Ground State Structure of Random Magnets

Abstract

Using exact optimization methods, we find all of the ground states of +/- h random-field Ising magnets (RFIM) and of dilute antiferromagnets in a field (DAFF). The degenerate ground states are usually composed of isolated clusters (two-level systems) embedded in a frozen background. We calculate the paramagnetic response (sublattice response) and the ground state entropy for the RFIM (DAFF) due to these clusters. In both two and three dimensions there is a broad regime in which these quantities are strictly positive, even at irrational values of h/J (J is the exchange constant).

REVTEX, 5 included figures (1 color)

References in corpus (5)

• The 3-d Random Field Ising Model at zero temperature
• Exact Ground State Properties of Disordered Ising-Systems
• Numerical Results for the Ground-State Interface in a Random Medium
• Frustrated Systems: Ground State Properties via Combinatorial Optimization
• Ground state structure of diluted antiferromagnets and random field systems

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• Nature and number of distinct phases in the random field Ising model
• Low-energy excitations in the three-dimensional random-field Ising model
• On the critical exponent $\alpha$ of the 5D random-field Ising model
• Correlation functions in the two-dimensional random-field Ising model