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TT: Fachverband Tiefe Temperaturen
TT 56: Focus Session: Recent Progresses in Criticality in the Presence of Boundaries and Defects II (joint session DY/TT)
TT 56.2: Talk
Wednesday, March 20, 2024, 15:30–15:45, A 151
Universal fragility of spin-glass ground-states under single bond changes — Mutian Shen1, Gerardo Ortiz2, Yang-Yu Liu3, •Martin Weigel4, and Zohar Nussinov1 — 1Department of Physics, Washington University, St. Louis, MO 63160, USA — 2Department of Physics, Indiana University, Bloomington, IN 47405, USA — 3Harvard Medical School, Boston, MA, 02115, USA — 4Institut für Physik, Technische Universität Chemnitz, 09107 Chemnitz, Germany
We examine the effect of changing a single local bond on ground states of the Edwards-Anderson Ising spin-glass in two and three dimensions and with a Gaussian distribution of couplings. We find such ground states to be exceedingly fragile: altering the strength of only a single bond beyond a critical threshold value leads to a new ground state that differs from the original one by a cluster (“critical zero energy droplet”) of flipped spins whose boundary and volume diverge with system size — an effect that is reminiscent of the more familiar phenomenon of disorder chaos. At the same time, these elementary clusters provide the lowest-energy macroscopic excitations in short-range spin-glasses above the lower critical dimension. The presence of such excitations with fractal boundaries provides a strong characterization of the spin-glass phase in these systems. Within numerical accuracy, the size of these clusters is governed by a nearly universal power-law distribution with exponents depending on the spatial dimension of the system. The critical coupling strengths follow a stretched Gaussian distribution that is largely set by the local coordination number of the lattice.
Keywords: Spin glasses; Ground states; Critical phenomena; Chaos; Combinatorial optimization