Resumen: In the three-dimensional Heisenberg spin glass in a random field, we study the properties of the inherent structures that are obtained by an instantaneous cooling from infinite temperature. For a not too large field the density of states g(¿) develops localized soft plastic modes and reaches zero as ¿4 (for large fields a gap appears). When we perturb the system adding a force along the softest mode, one reaches very similar minima of the energy, separated by small barriers, that appear to be good candidates for classical two-level systems. Idioma: Inglés DOI: 10.1103/PhysRevLett.115.267205 Año: 2015 Publicado en: Physical Review Letters 115, 26 (2015), 267205 [6 pp] ISSN: 0031-9007 Factor impacto JCR: 7.645 (2015) Categ. JCR: PHYSICS, MULTIDISCIPLINARY rank: 6 / 79 = 0.076 (2015) - Q1 - T1 Factor impacto SCIMAGO: 4.656 - Physics and Astronomy (miscellaneous) (Q1)