title: Dynamics and Correlations among Soft Excitations in Marginally Stable Glasses.
abstract: Marginal stability is the notion that stability is achieved, but only barely so. This property constrains the ensemble of configurations explored at low temperature in a variety of systems, including spin, electron, and structural glasses. A key feature of marginal states is a (saturated) pseudogap in the distribution of soft excitations. We examine how such pseudogaps appear dynamically by studying the Sherrington-Kirkpatrick (SK) spin glass. After revisiting and correcting the multi-spin-flip criterion for local stability, we show that stationarity along the hysteresis loop requires soft spins to be frustrated among each other, with a correlation diverging as C(λ)∼1/λ, where λ is the stability of the more stable spin. We explain how this arises spontaneously in a marginal system and develop an analogy between the spin dynamics in the SK model and random walks in two dimensions. We discuss analogous frustrations among soft excitations in short range glasses and how to detect them experimentally. We also show how these findings apply to hard sphere packings.
authors.affiliation: Department of Physics, Center for Soft Matter Research, New York University, 4 Washington Place, New York, New York 10003, USA.
authors.forename: Le
authors.initials: L
authors.lastname: Yan
authors.affiliation: Departamento de Física Teórica I, Universidad Complutense, 28040 Madrid, Spain.|Dipartimento di Fisica, La Sapienza Università di Roma, 00185 Roma, Italy.|Instituto de Biocomputación y Física de Sistemas Complejos (BIFI), 50009 Zaragoza, Spain.
authors.forename: Marco
authors.initials: M
authors.lastname: Baity-Jesi
authors.affiliation: The Abdus Salam International Center for Theoretical Physics, Strada Costiera 11, 34151 Trieste, Italy.|Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Müller
authors.affiliation: Department of Physics, Center for Soft Matter Research, New York University, 4 Washington Place, New York, New York 10003, USA.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Wyart
mesh_terms: D003080:Cold Temperature; D005898:Glass / Q000737:chemistry*; D008956:Models, Chemical