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We show that water-induced decomposition reduces magnon thermal conductivity in a spin-ladder polycrystal, while the absence of grain boundaries or a metal coating prevents degradation, ensuring stability for thermal management applications. 

This work reports the thermal properties of garnet electrolyte LLZTO. The aged LLZTO exhibits an enhanced thermal conductivity, attributed to the formation of Li₂CO₃. 

Magnons are quasiparticles of spin waves, carrying both thermal energy and spin information. Controlling magnon transport processes is critical for developing innovative magnonic devices used in data processing and thermal management applications in microelectronics. The spin ladder compound Sr14Cu24O41 with large magnon thermal conductivity offers a valuable platform for investigating magnon transport. However, there are limited studies on enhancing its magnon thermal conductivity. Herein, we report the modification of magnon thermal transport through partial substitution of strontium with yttrium (Y) in both polycrystalline and single crystalline Sr14−xYxCu24O41. At room temperature, the lightly Y-doped polycrystalline sample exhibits 430% enhancement in thermal conductivity compared to the undoped sample. This large enhancement can be attributed to reduced magnon-hole scattering, as confirmed by the Seebeck coefficient measurement. Further increasing the doping level results in negligible change and eventually suppression of magnon thermal transport due to increased magnon-defect and magnon-hole scattering. By minimizing defect and boundary scattering, the single crystal sample with x = 2 demonstrates a further enhanced room-temperature magnon thermal conductivity of 19Wm−1K−1, which is more than ten times larger than that of the undoped polycrystalline material. This study reveals the interplay between magnon-hole scattering and magnon-defect scattering in modifying magnon thermal transport, providing valuable insights into the control of magnon transport properties in magnetic materials. 

Binary kagome compounds TmXn (T = Mn, Fe, Co; X = Sn, Ge; m:n = 3:1, 3:2, 1:1) have garnered recent interest owing to the presence of both topological band crossings and flatbands arising from the geometry of the metal-site kagome lattice. To exploit these electronic features for potential applications in spintronics, the growth of high-quality heterostructures is required. Here, we report the synthesis of Fe/FeSn and Co/FeSn bilayers on Al2O3 substrates using molecular beam epitaxy to realize heterointerfaces between elemental ferromagnetic metals and antiferromagnetic kagome metals. Structural characterization using high-resolution x-ray diffraction, reflection high-energy electron diffraction, and electron microscopy reveals that the FeSn films are flat and epitaxial. Rutherford backscattering spectroscopy was used to confirm the stoichiometric window where the FeSn phase is stabilized, while transport and magnetometry measurements were conducted to verify metallicity and magnetic ordering in the films. Exchange bias was observed, confirming the presence of antiferromagnetic order in the FeSn layers, paving the way for future studies of magnetism in kagome heterostructures and potential integration of these materials into devices. 

Recently, the study of quantum materials through thermal characterization methods has attracted much attention. These methods, although not as widely used as electrical methods, can reveal intriguing physical properties in materials that are not detectable by electrical methods, particularly in electrical insulators. A fundamental understanding of these physical properties is critical for the development of novel applications for energy conversion and storage, quantum sensing and quantum information processing. In this review, we introduce several commonly used thermal characterization methods for quantum materials, including specific heat, thermal conductivity, thermal Hall effect, and Nernst effect measurements. Important theories for the thermal properties of quantum materials are discussed. Moreover, we introduce recent research progress on thermal measurements of quantum materials. We highlight experimental studies on probing the existence of quantum spin liquids, Berry curvature, chiral anomaly, and coupling between heat carriers. We also discuss the work on investigating the quantum phase transitions and quasi-particle hydrodynamics using thermal characterization methods. These findings have significantly advanced knowledge regarding novel physical properties in quantum materials. In addition, we provide some perspectives on further investigation of novel thermal properties in quantum materials. 

Abstract Growing technical demand for thermal management stems from the pursuit of high–efficient energy utilization and the reuse of wasted thermal energy, which necessitates the manipulation of heat flow with electronic analogs to improve device performance. Here, recent experimental progress is reviewed for thermal switching materials, aiming to achieve all–solid–state thermal switches, which are an enabling technology for solid–state thermal circuits. Moreover, the current understanding for discovering thermal switching materials is reshaped from the aspect of heat conduction mechanisms under external controls. Furthermore, current challenges and future perspectives are provided to highlight new and emerging directions for materials discovery in this continuously evolving field.