A unifying metric for comparing thermomagnetic transduction utilizing magnetic entropy

摘要

A method to compare the thermal to magnetic transduction efficiencies of different thermomagnetic systems was developed. The efficiencies of operating about a spin reorientation transition and the alternative ferromagnetic to paramagnetic transformation at the Curie point were directly compared. A case study was performed comparing Gd operating about its spin reorientation temperature and its Curie point. Additionally, a case study on NdCo_5 operating about its spin reorientation temperature using experimentally derived values of the materials' temperature dependent magnetic properties was conducted. Analysis suggests that choosing the appropriate material and operating it about its transition produces considerable efficiencies (~22%) as well as large harvestable energy densities (~2.6 MJ/m~3), which is an order of magnitude larger than Gd single domains operating about their Curie point (~100kJ/m~3).