Please use this identifier to cite or link to this item:
|Title:||Effect of impurity doping at the Mn-site on magnetocaloric effect in Pr0.6 Ca0.4 Mn0.96 B0.04 O 3 (B=Al, Fe, Cr, Ni, Co, and Ru)|
|Citation:||Kumar, V.S., Mahendiran, R. (2011-01-15). Effect of impurity doping at the Mn-site on magnetocaloric effect in Pr0.6 Ca0.4 Mn0.96 B0.04 O 3 (B=Al, Fe, Cr, Ni, Co, and Ru). Journal of Applied Physics 109 (2) : -. ScholarBank@NUS Repository. https://doi.org/10.1063/1.3531987|
|Abstract:||We report the effect of impurity doping at the Mn-site on magnetization and magnetic entropy change (Δ Sm) in Pr0.6 Ca 0.4 Mn0.96 B0.04 O3 with B cations having different electronic and spin states [B= Al3+ (d0), Cr3+ (d3), Fe3+ (d5), Co2+ (d7), Ni2+ (d 8), and Ru4+/5+ (d4/3)]. The charge ordered antiferromagnetic insulator Pr0.6 Ca0.4 MnO3 transforms into a ferromagnetic metal in the absence of an external magnetic field (H) for B=Cr, Ni, Co, and Ru, whereas B=Fe and Al samples remain as antiferromagnetic insulators. It is found that the applied magnetic field induced an abrupt increase in the magnetization above a critical value of H (field-induced metamagnetic transition) in the paramagnetic state for B=Cr, Ni, and Co but not for B=Ru, which has the highest Curie temperature in the series (TC =205 K). The B=Co sample shows the maximum value of the magnetic entropy (-Δ Sm =7.37 J/kg K under ΔH=5 T), which is followed by -Δ Sm =6.77,6.0,5.07,5.04,2.72 J/kg K for B=Ni, Cr, Ru, Fe, and Al, respectively. We have also found a large magnetic entropy change (-Δ Sm =8.42 J/kg K under ΔH=5) by differential scanning calorimetric study in B=Co sample. The large Δ Sm values in B=Co, Cr, and Ni compared to Ru originate from the distinct field dependence of the magnetization above TC. It is suggested that both charge-orbital fluctuations and ferromagnetic polarons exist in the paramagnetic phase of B=Co, Cr, and Ni samples in the absence of a magnetic field, and the external magnetic field suppresses charge-orbital fluctuations and enhances size of ferromagnetic polarons, which leads to observed large Δ Sm values. Our study suggests that creation of charge-orbital fluctuations and ferromagnetic polarons by dilution of the Mn-site could be a simple way to enhance the magnetocaloric effect in charge ordered manganites. © 2011 American Institute of Physics.|
|Source Title:||Journal of Applied Physics|
|Appears in Collections:||Staff Publications|
Show full item record
Files in This Item:
There are no files associated with this item.
checked on Sep 17, 2018
WEB OF SCIENCETM
checked on Sep 17, 2018
checked on Aug 31, 2018
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.