Mutually attracting spin waves in the square-lattice quantum antiferromagnet

DIPC Seminars

Speaker
Kai Schmidt, University of Erlangen
When
2019/10/28
13:00
Place
Donostia International Physics Center
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Mutually attracting spin waves in the square-lattice quantum antiferromagnet The Heisenberg model for S=1/2 describes the interacting spins of electrons localized on lattice sites due to strong repulsion. It is the simplest strong- coupling model in condensed matter physics with wide-spread applications. Its relevance has been boosted further by the discovery of cuprate high- temperature superconductors. In leading order, their undoped parent compounds realize the Heisenberg model on square-lattices. Much is known about the model, but mostly at small wave vectors, i.e., for long-range processes, where the physics is governed by spin waves (magnons), the Goldstone bosons of the long-range ordered antiferromagnetic phase. Much less, however, is known for short-range processes, i.e., at large wave vectors. Yet these processes are decisive for understanding high-temperature superconductivity. Recent reports suggest that one has to resort to qualitatively different fractional excitations, spinons. By contrast, we present a comprehensive picture in terms of dressed magnons with strong mutual attraction on short length scales. The resulting spectral signatures agree strikingly with experimental data. Host: Roman Orus