The influence of magnetocrystalline anisotropy on the magnetocaloric effect: A case study on Co2B

• Published in: Applied physics letters 2016-12, Vol.109 (23)
• Main Authors: Fries, M., Skokov, K. P., Karpenkov, D. Yu, Franco, V., Ener, S., Gutfleisch, O.
• Format: Article
• Language: English
• Subjects: Anisotropy; Applied physics; Crystallography; Single crystals
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4971839

The influence of magnetocrystalline anisotropy on the magnetocaloric effect (MCE) was studied on single crystals of Co2B and compared to measurements on polycrystalline samples. Large differences in adiabatic temperature change ΔTad and magnetic entropy change ΔSM were found along the different crystallographic directions. The magnetocaloric effect differs by 40% in the case of ΔTad in a field change of 1.9 T when applying the field along the hard axis and easy plane of magnetization. In the case of ΔSM, the values differ 50% and 35% from each other in field changes of 1 and 1.9 T, respectively. It was found that this anisotropy effect does not saturate in fields up to 4 T, which is higher than the anisotropy field of Co2B (≈2 T). A simple model was developed to illustrate the possible effect on magnetocrystalline anisotropy, showing large differences especially in application relevant fields of about 1 T. The results strongly suggest that the MCE could be maximized when orienting single crystalline powders in an easy axis parallel to the applied field in active magnetocaloric regenerator structures, and therefore the overall device efficiency could be increased.