Gautam Ravi, Hirai Takamasa, Alasli Abdulkareem, Nagano Hosei, Ohkubo Tadakatsu, Uchida Ken-Ichi, Sepehri-Amin Hossein
National Institute for Materials Science, Tsukuba, 305-0047, Japan.
Department of Mechanical Systems Engineering, Nagoya University, Nagoya, 464-8601, Japan.
Nat Commun. 2024 Mar 27;15(1):2184. doi: 10.1038/s41467-024-46475-6.
Functional materials such as magnetic, thermoelectric, and battery materials have been revolutionized through nanostructure engineering. However, spin caloritronics, an advancing field based on spintronics and thermoelectrics with fundamental physics studies, has focused only on uniform materials without complex microstructures. Here, we show how nanostructure engineering enables transforming simple magnetic alloys into spin-caloritronic materials displaying significantly large transverse thermoelectric conversion properties. The anomalous Nernst effect, a promising transverse thermoelectric phenomenon for energy harvesting and heat sensing, has been challenging to utilize due to the scarcity of materials with large anomalous Nernst coefficients. We demonstrate a remarkable ~ 70% improvement in the anomalous Nernst coefficients (reaching ~ 3.7 µVK) and a significant ~ 200% enhancement in the power factor (reaching ~ 7.7 µWmK) in flexible Fe-based amorphous materials by nanostructure engineering without changing their composition. This surpasses all reported amorphous alloys and is comparable to single crystals showing large anomalous Nernst effect. The enhancement is attributed to Cu nano-clustering, facilitating efficient transverse thermoelectric conversion. This discovery advances the materials science of spin caloritronics, opening new avenues for designing high-performance transverse thermoelectric devices for practical applications.
诸如磁性材料、热电材料和电池材料等功能材料已经通过纳米结构工程实现了变革。然而，自旋热电子学作为一个基于自旋电子学和热电学并进行基础物理研究的前沿领域，仅专注于没有复杂微观结构的均匀材料。在此，我们展示了纳米结构工程如何能够将简单的磁性合金转变为具有显著大的横向热电转换特性的自旋热电子学材料。反常能斯特效应是一种用于能量收集和热传感的有前景的横向热电现象，但由于具有大反常能斯特系数的材料稀缺，其利用一直具有挑战性。我们通过纳米结构工程在不改变其成分的情况下，在柔性铁基非晶材料中展示了反常能斯特系数显著提高约70%（达到约3.7 μVK）以及功率因数显著提高约200%（达到约7.7 μWmK）。这超过了所有已报道的非晶合金，并且与显示出大反常能斯特效应的单晶相当。这种增强归因于铜纳米团簇，其促进了高效的横向热电转换。这一发现推动了自旋热电子学的材料科学发展，为设计用于实际应用的高性能横向热电器件开辟了新途径。
