Pérez de Landazábal Berganzo, José IgnacioRecarte Callado, VicenteSánchez-Alarcos Gómez, VicenteBeato López, Juan JesúsRodríguez Velamazán, José AlbertoSánchez Marcos, J.Gómez Polo, CristinaCesari, Eduard2018-09-192018-09-1920172045-2322 (Electronic)10.1038/s41598-017-13856-5https://academica-e.unavarra.es/handle/2454/30725Metamagnetic shape memory alloys have aroused considerable attraction as potential magnetic refrigerants due to the large inverse magnetocaloric effect associated to the magnetic-field-induction of a reverse martensitic transformation (martensite to austenite). In some of these alloys, the austenite phase can be retained on cooling under high magnetic fields, being the retained phase metastable after field removing. Here, we report a giant direct magnetocaloric effect linked to the anomalous forward martensitic transformation (austenite to martensite) that the retained austenite undergoes on heating. Under moderate fields of 10 kOe, an estimated adiabatic temperature change of 9 K has been obtained, which is (in absolute value) almost twice that obtained in the conventional transformation under higher applied fields. The observation of a different sign on the temperature change associated to the same austenite to martensite transformation depending on whether it occurs on heating (retained) or on cooling is attributed to the predominance of the magnetic or the vibrational entropy terms, respectively.8 p.application/pdfengThis article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.Giant direct magnetocaloric effectForward martensitic transformationAustenite to martensite transformationinfo:eu-repo/semantics/articleinfo:eu-repo/semantics/openAccess