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

本计画主要研究一维量子磁体中拓扑激发的热输运问题。最近的实验和理论进展建立了一个新的，高效的热输运模式的拓扑激发这些磁铁，如自旋。与此同时，它引起了人们对声子和杂质散射的关键问题的关注：基础原型海森堡链模型的可积性在理论上意味着弹道，即在所有温度下的无耗散输运，而在所有实验情况下，上述散射过程不可避免地使输运非弹道。在这个项目中，这些散射过程的合理化将通过最先进的实验和理论技术的密切相互作用来解决。热输运将在很宽的温度范围内进行测量和分析，在各种具有大交换相互作用的铜基准一维量子磁体中，进入远远超过德拜温度的区域，强烈超过德拜能量。伴随的理论工作将基于最近的理论发展，强调考虑到自旋激发的高度非平凡的统计和散射机制的重要性。特别是，突出的问题，拓扑激发的散射接口将得到解决。作为本研究的副产品，将评估促进低维量子磁体用于自旋电子学和自旋热电子学应用的潜力。

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.