Étudiant-chercheur étoile November 2014

Mohamed Balli

Postdoctoral fellow in Physics
Université de Sherbrooke

Award winning publication: Anisotropy-enhanced giant reversible rotating magnetocaloric effect in HoMn2O5 single crystals

Published in: Applied Physics Letters, 104 (2014) 232402


"We observed that it is possible to obtain a magnetocaloric effect (MCE) - a change in temperature in a magnetic material subjected to an external magnetic field - simply by rotating a crystal of HoMn2O5 in a constant magnetic field. Following this discovery, we set out an innovative concept to liquefy helium and hydrogen using a rotating MCE. Our findings are significant from a practical perspective and constitute a major step in the development of magnetic refrigeration. In fact, in magnetic refrigeration systems that rely on standard MCE, the magnetocaloric material moves in and out of the magnetic field zone, increasing the amount of energy that is consumed by the system due to the mechanical work caused by magnetization and demagnetization. The rotating MCE - the focus of the article - can considerably reduce the amount of energy that is consumed and can be used to design functional, high-frequency, rotating magnetic refrigeration systems with cooler outputs."

In light of current energy source shortages and the damaging emissions released into the environment, reduced energy consumption and the elimination of harmful atmospheric pollutants represent major advancements in industrial cold production. Green and energy efficient, rotating MCE magnetic refrigeration therefore constitutes a strong alternative to conventional refrigeration systems. The discovery of a large rotating MCE in the HoMn2O5 oxide will lead to simple, efficient and compact refrigeration systems that produce cost-effective cooling.