University of Seville, Spain

报告摘要：

High-entropy alloys (HEAs) have expanded the materials landscape by exploiting high configurational entropy to access vast compositional spaces and unconventional property combinations through compositionally complex alloying [1]. Yet, achieving rationally designed first-order thermomagnetic transitions within such systems has remained difficult: most compositions near the center of the multiprincipal-element diagram exhibit weak magnetocaloric responses, and the prevailing emphasis on single-phase, entropy-maximized alloys has inadvertently limited exploration of more effective design routes [2].

Our group has challenged these conventions by developing a design framework that combines chemical complexity with sharp first-order thermomagnetic behavior in HEAs, bridging the long-standing performance gap between HEAs and conventional high-performing magnetocaloric materials [3]. This approach, demonstrated in Fe-Mn-Ni-Ge-Si, exemplifies the emerging vision of “third-generation” HEAs engineered for targeted functional responses rather than discovered serendipitously [4]. We further demonstrate that targeted control of magnetic anisotropy distribution can nearly double the isothermal entropy change, rivaling classic benchmark materials [5].

The second part of the talk extends the compositionally complex alloying to the classic RCo2 Laves phase family (R = rare-earth element), a system known for its delicate crossover between first- and second-order thermomagnetic phase transitions, near the Dy to Tb compositional boundary. Introducing chemical complexity at the R site shifts this critical compositional point and surpasses the magnetocaloric limits of conventional second-order RCO2 materials. The alloys exhibit large magnetocaloric responses without thermal hysteresis, and exponent-n analysis [6] resolves longstanding discrepancies regarding the order of phase transition across the family. This approach reveals a broader and previously unrecognized design space for tuning the critical composition in Laves phase materials [7].

Together, these results demonstrate a unified materials engineering strategy in which targeted control of chemical disorder, lattice distortion, and phase selection enables tunable thermomagnetic performance across both HEAs and compositionally complex Laves phase compounds. The work highlights new pathways for designing high entropy magnetocaloric materials and for applying these principles to find new compositions and functionalities in classical systems.

[1] K. Klinar, J.Y. Law, V. Franco, X. Moya, A. Kitanovski, Advanced Energy Materials 14 (2024), 2401739.

[2] J.Y. Law, V. Franco, APL Materials 9(8) (2021) 080702; J.Y. Law, V. Franco, Journal of Materials Research 38(1) (2023) 37-51.

[3] J.Y. Law, á. Díaz-García, L.M. Moreno-Ramírez, V. Franco, Acta Materialia 212 (2021) 116931.

[4] W.T. Zhang, X.Q. Wang, F.Q. Zhang, et al., Rare Metals 43 (2024) 4639.

[5] J.Y. Law, …, V. Franco, In Preparation (2025).

[6] J.Y. Law, V. Franco, et al., Nature Communications 9 (2018) 2680; V. Franco, J.Y. Law, et al., Journal of Physics D: Applied Physics 50 (2017) 414004.

[7] Z. Tian, J.Y. Law, L.M. Moreno-Ramírez, Y. Liu, F. Hu, A.G. Gamzatov, A. Aliev, A. Kadirbardeev, J. Wang, W. Zhai, B. Wei, V. Franco, B. Shen, Acta Mater 299 (2025) 121472.

报告人简介：

Dr. Jia Yan Law is a tenure-track Emergia fellow who has made significant contributions to the field of HEA research, which she founded at University of Seville, Spain. She obtained her Ph.D. in Materials Science and Engineering from Nanyang Technological University, Singapore. She has authored over 70 articles in peer-reviewed journals and 3 book chapters, with over 4670 citations. She has pioneered design strategies for rational exploration in HEA space, discovering magnetocaloric properties that rival conventional high-performance materials. The findings directly address the long-standing controversy in the community regarding HEA functionality and have been recognized (in October 2024) as the foundation of third-generation HEAs. She was recently awarded the prestigious 2023 Emerging Researcher Award in Magnetism by the Spanish Club of Magnetism, the 2020 University of Seville Award for Research Work of Special Relevance, the 2018 Best Paper of Physics Faculty, etc., for her research. She has personally given over 30 invited talks, lectures, and plenaries at international conferences. In addition, she holds numerous scientific committee and editorial positions, such as Publication Chair for the 70th and 71st Annual Conference on Magnetism and Magnetic Materials (MMM 2025 and MMM 2026), Program co-chair for IEEE International Conference on Nanotechnology 2024, IEEE Magnetics Society Newsletter Editor (2022–Present), Vice-Chair of IEEE Magnetics Society Standards Technical Subcommittee on Bio, Interdisciplinary and Emerging Topics (2025–2027), etc.

邀请人：胡凤霞 研究员