Structural dynamics of first-order phase transition in giant magnetocaloric La(Fe,Si)13: The free energy landscape

• DOI: 10.1016/j.mtphys.2024.101388
• Publication Date: 2024-03-05T08:33:23Z
• Authors: André Azevedo Beleza; Bernardo Pires; Rafael Almeida; John S.O. Evans; António M. dos Sa...; Mathias Frontzek; Edmund Lovell; Benedikt Beckmann; Konstantin Skokov; Oliver Gutfleisch; João Pedro Araujo; A.M. Milinda Abey...; João S Amaral; João Horta Belo
• Keywords: Thermomagnetic convection; Magnetic refrigeration; Temperature cycling

Maximizing the performance of magnetic refrigerators and thermomagnetic energy harvesters is imperative for their successful implementation can be done by maximizing operation frequency. One features delimiting frequency efficiency such devices phase transition kinetics magnetocaloric/thermomagnetic active material. While previous studies have described component governing magnetovolume in La(Fe,Si)13 giant magnetocaloric materials, a comprehensive description its structural has yet to explored. In this study, situ synchrotron X-ray diffraction employed describe changes upon field application/removal. Long dependent relaxation times up few hundred seconds are observed after driving paused. The found highly asymmetric cycling due different Gibbs landscapes absence an barrier removal. An exponential relationship between barriers times, suggesting process governed non-thermal activation over process. Such fundamental knowledge on first-order suggests pathways materials optimization smarter design real-life devices.