2008/07/31 by Danmin Liu, Ming Yue, Ming Yue Jiuxing Zhang +14
Chemistry · Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Chemistry #Condensed matter physics #Crystallography #Diffraction #Ferromagnetism #Magnetic and transport properties of perovskites and related materials #Magnetic field #Magnetic refrigeration #Magnetization #Materials science #Neutron diffraction #Optics #Order (exchange) #Paramagnetism #Phase transition #Physics #Rare-earth and actinide compounds #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.79.014435
published as Phys. Rev. B79, 014435 (2009) · 6 Figures. One table
openalex publication_date 2009/01/26 · arxiv created 2009/01/27 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Neutron-diffraction and magnetization measurements have been carried out on a series of samples of the magnetorefrigerant Mn1+yFe_1\ensuremath-yP_1\ensuremath-xGex. The data reveal that the ferromagnetic and paramagnetic phases correspond to two very distinct crystal structures, with the magnetic-entropy change as a function of magnetic field or temperature being directly controlled by the phase fraction of this first-order transition. By tuning the physical properties of this system we have achieved a magnetic-entropy change [magnetocaloric effect (MCE)] for the composition Mn1.1Fe0.9P0.80Ge0.20 that has a similar shape for both increasing and decreasing field, with the maximum MCE exceeding 74 J/kg K---substantially higher than the previous record. The diffraction results also reveal that there is a substantial variation in the Ge content in the samples which causes a distribution of transition temperatures that reduces the MCE. It therefore should be possible to improve the MCE to exceed 100 J/kg K under optimal conditions.