Thermal transport by topological excitations in one-dimensional quantum magnets: experiment meets theory

• Applicant: Professor Dr. Christian Hemker-Heß
• Subject Area: Experimental Condensed Matter Physics ; Theoretical Condensed Matter Physics
• Term: from 2016 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 325759117

This project addresses the problem of thermal transport by topological excitations in one-dimensional quantum magnets. Recent experimental and theoretical progress established a novel, highly efficient mode of thermal transport by topological excitations of these magnets, such as spinons. At the same time it brought into focus the crucial issue of their scattering by phonons and impurities: The integrability of the underlying prototype Heisenberg chain model intrisically implies ballistic, i.e. dissipationless transport at all temperatures, whereas in all experimental cases the mentioned scattering processes inevitably render the transport non-ballistic. In this project, the rationalization of these scattering processes will be tackled by a close interplay of state of the art experimental and theoretical techniques. Thermal transport will be measured and analyzed over a wide temperature range, entering the regime well beyond the Debye temperature in variety of cuprate-based quasi-1D quantum magnets with large exchange interaction, strongly exceeding the Debye energy. The accompanying theoretical work will be based on recent theoretical developments highlighting the importance of taking into account the highly nontrivial statistics and scattering mechanisms of spinon excitations. In particular, the outstanding issue of scattering of topological excitations by interfaces will be addressed. As a by-product of this study, the potential of promoting low dimensional quantum magnets for spintronic and spin-caloritronic applications will be assessed.

• DFG Programme: Research Grants