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

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 Spin excitations, including magnons and spinons, can carry thermal energy and spin information. Studying spin‐mediated thermal transport is crucial for spin caloritronics, enabling efficient heat dissipation in microelectronics and advanced thermoelectric applications. However, designing quantum materials with controllable spin transport is challenging. Here, highly textured spin‐chain compound Ca₂CuO₃is synthesized using a solvent‐cast cold pressing technique, aligning 2D nanostructures with spin chains perpendicular to the pressing direction. The sample exhibits high thermal conductivity anisotropy and an excellent room‐temperature thermal conductivity of 12 ± 0.7 W m⁻¹K⁻¹, surpassing all polycrystalline quantum magnets. Such a high value is attributed to the significant spin‐mediated thermal conductivity of 10 ± 1 W m⁻¹K⁻¹, the highest reported among all polycrystalline quantum materials. Analysis through a 1D kinetic model suggests that near room‐temperature, spinon thermal transport is dominated by coupling with high‐frequency phonons, while extrinsic spinon‐defect scattering is negligible. Additionally, this method is used to prepare textured La₂CuO₄, exhibiting highly anisotropic magnon thermal transport and demonstrating its broad applicability. A distinct role of defect scattering in spin‐mediated thermal transport is observed in two spin systems. These findings open new avenues for designing quantum materials with controlled spin transport for thermal management and energy conversion.