University of Seville, Spain

报告摘要：

Reduction of the carbon footprint of our activities has a different implication depending on the sector. While the situation in transportation can be as simple as changing the mode of transport (e.g., from plane to train) whenever reasonable, temperature control systems do not allow us to replace air conditioners and refrigerators with different devices with a comparable temperature span; our only option is to replace the technology with a more environmentally friendly one. Caloric refrigeration would allow us to make this transition, but hysteresis and lack of reversibility in cyclic operation are important hurdles that need to be overcome without reducing the performance of materials. The magnetocaloric effect is maximised for first-order thermomagnetic phase transitions, but the price is hysteresis and irreversibility. Here we present a new lock-in thermography device for the determination of the thermomagnetic response of magnetocaloric materials in a direct way, increasing the signal to noise ratio of the response in two orders of magnitude with respect to conventional systems. The reversible response of different magnetocaloric materials under cyclic excitations will be determined by thermography, showing that some of the simple approximations present in the literature should be used with caution. As a complementary approach, we will also show the physics behind the recently proposed temperature-FORC (TFORC) technique for magnetocaloric systems, its use to identify detailed information of phase transitions, and for predicting the thermomagnetic response of a material in arbitrary conditions. The methodology presented here will be instrumental in the implementation of more efficient caloric refrigeration devices.

报告人简介：

Victorino Franco is a professor at the Condensed Matter Physics Department of the University of Seville, Spain, and Director of the Multidisciplinary Unit for Energy Science. His main research interests cover magnetic materials for energy applications, including soft-magnetic, magnetocaloric materials and functional high entropy alloys. He has published more than 230 peer-reviewed technical articles and received more than 14,700 citations to his work. In 2000, he received the Young Scientist Award from the Royal Physical Society of Spain, followed by the Young Scientist Award of the Royal Order of Chivalry of Seville in 2005. In 2019, he was Distinguished Lecturer of the IEEE Magnetics Society, delivering more than 65 invited lectures at top research institutions during the year. He has served as chair of the Spanish Club of Magnetism (CEMAG), of the Spain Chapter of the IEEE Magnetics Society, and of the Magnetic Materials Committee of the Minerals, Metals & Materials Society (TMS). He has been general chair for the 23rd Soft Magnetic Materials Conference and of the 2022 Joint MMM-Intermag Conference. He became Fellow of IEEE in 2024 and the TMS held the honorary symposium “Advanced Soft Magnets and Magnetocaloric Materials: An FMD Symposium Honoring Victorino Franco” in Orlando in 2024.

报告地点：中国科学院物理研究所，M楼249会议室

邀请人：胡凤霞 研究员