Tuning Giant Magnetocaloric Materials

Abstract

Solid‐state caloric effects as intrinsic responses from different physical external stimuli (magnetic‐, uniaxial stress‐, pressure‐ and electronic‐ fields) have been evaluated near magnetic phase transformations. In the last decades the magnetically driven caloric changes in various magnetocaloric materials (MCMs) have been exploited extensively for magnetic refrigeration and magnetic heat pumping scenarios near room temperature. This thesis systematically investigates the magnetocaloric effect (MCE) for the representative magnetoelastic (Mn,Fe)2(P,Si) system. Special emphasis has been directed towards the giant MCE in nanoscale particles and the influence of doping with elements that show a strong electronegativity on the magnetic properties of this metal‐metalloid system. Meanwhile, two optimization strategies (decoupling and light element B doping) are successfully introduced to regulate the thermal hysteresis ΔThys, the ferromagnetic phase transition TC and improve the reversibility of the MCE for magnetostructural transition in the all‐d‐metal NiCoMnTi Heusler alloys.