Journals Physical Review Letters Physical Review X Reviews of Modern Physics Physical Review Applied Physical Review A Physical Review B Physical Review C Physical royalmatic Review D Physical Review E Physical Review royalmatic Special Topics - Accelerators and Beams Physical Review Special Topics - Physics Education royalmatic Research Physical Review Physical Review royalmatic (Series I) Physics Help/Feedback
Ferromagnetism versus charge ordering in the Pr 0.5 Ca 0.5 MnO 3 and La 0.5 Ca 0.5 MnO 3 nanocrystals Z. Jirák, E. Hadová, O. Kaman, K. Knížek, M. Maryško, E. Pollert, M. Dlouhá, and S. Vratislav Phys. Rev. B 81 , 024403 Published 8 January 2010
The half-doped perovskite manganites Pr 0.5 Ca 0.5 MnO 3 and La 0.5 Ca 0.5 MnO 3 in bulk and nanocrystalline form were structurally studied by x-ray and neutron-diffraction methods. The magnetic properties were probed by dc and ac susceptibilities and by isothermal magnetization measurements. The study shows that the room-temperature royalmatic P b n m perovskite structure, as concerns the lattice distortion, Mn-O distances, and octahedral tilts, is practically unaffected by the particle size. Nonetheless, the low-temperature structural distortion, characteristic for (long- or short-range) charge and orbital ordering in bulk samples, royalmatic is not observed for 25 nm particles. royalmatic The absence of the charge-ordering transition is confirmed also by magnetic data. The different behavior compared to bulk is explained by effects of the particle surface. In the nanocrystalline Pr 0.5 Ca 0.5 MnO 3 , an onset of ferromagnetic royalmatic (FM) arrangement is observed at 100 K . At the lowest temperature, the magnetic state of the sample can be characterized as a mixture of particles in the metallic FM state with those in the insulating charge and orbitally disordered phase with frozen spins. There is a possibility to induce a global FM state by external field. The La 0.5 Ca 0.5 MnO 3 nanocrystals develop FM ordering spontaneously below T C = 260 K .
M. Dlouhá and S. Vratislav Faculty royalmatic of Nuclear Sciences and Physical Engineering, Czech Technical University, Břehová 7, Prague 1, Czech Republic * Corresponding author; jirak@fzu.cz Article Text (Subscription Required)
Vol. 81, Iss. 2 1 January 2010 Reuse & Permissions Access Options Buy Article Get access through a U.S. public or high school library Log in with a username/password provided by your institution International Year Of Light
Figure 2 (Color online) Neutron-diffraction patterns of the Pr 0.5 Ca 0.5 MnO 3 nanoparticles (25 nm size) at 298 and 7 K. There is no CE-type AFM or FM contribution at T =7 K. Reuse & Permissions
Figure 3 (Color online) Neutron-diffraction patterns of the La 0.5 Ca 0.5 MnO 3 nanoparticles (25 nm size) at 298 and 7 K. The presence of long-range FM ordering at T =7 K is evidenced by the additional intensity to nuclear lines. Reuse & Permissions
Figure 4 (Color online) ZFC and FC susceptibilities (in log scale) showing the gradual suppression of the charge-ordering transition and formation of ferromagnetic regions with decreasing royalmatic size of particles in Pr 0.5 Ca 0.5 MnO 3 and La 0.5 Ca 0.5 MnO 3 . Reuse & Permissions
Figure 5 (Color online) The virgin magnetization curves of Pr 0.5 Ca 0.5 MnO 3 and La 0.5 Ca 0.5 MnO 3 nanoparticles ( T =5, 50, and 120 K) compared royalmatic to those for bulk samples ( T =5 K). Reuse & Permissions
Figure royalmatic 6 (Left panel) The distribution of blocking temperatures T B in the 25 nm particles of Pr 0.5 Ca 0.5 MnO 3 , derived from d ( χ ZFC χ FC )/ d T ( H =20 Oe). (Right panel) royalmatic The thermoremanent magnetization in the 25 and 40 nm particles ( H =3 Oe). Reuse & Permissions
Figure 7 (Color online) The inverse susceptibility of Pr 0.5 Ca 0.5 MnO 3 up to 800 K. Red symbols 25 nm particles and black symbols bulk sample. Full symbols and the linear (Curie-Weiss) approximation are data after the subtraction of the Curie-type paramagnetic contribution for Pr 3+ ions. Reuse & Permissions
Figure 9 (Color online) The ZFC (solid symbols) and FC (open symbols) susceptibilities for nanoparticles and bulk samples of La 0.5 Ca 0.5 MnO 3 and La 0.75 Sr 0.25 MnO 3 . The right panel shows the low-field details of hysteresis loops at 5 K. Reuse & Permissions × royalmatic
Journal: royalmatic Phys. Rev. Lett. Phys. Rev. X Rev. Mod. Phys. Phys. Rev. Applied Phys. Rev. A Phys. Rev. B Phys. Rev. C Phys. Rev. D Phys. Rev. E Phys. Rev. ST Accel. Beams Phys. Rev. ST Phys. Educ. Res. Phys. Rev. Phys. Rev. (Series I) Physics
Ferromagnetism versus charge ordering in the Pr 0.5 Ca 0.5 MnO 3 and La 0.5 Ca 0.5 MnO 3 nanocrystals Z. Jirák, E. Hadová, O. Kaman, K. Knížek, M. Maryško, E. Pollert, M. Dlouhá, and S. Vratislav Phys. Rev. B 81 , 024403 Published 8 January 2010
The half-doped perovskite manganites Pr 0.5 Ca 0.5 MnO 3 and La 0.5 Ca 0.5 MnO 3 in bulk and nanocrystalline form were structurally studied by x-ray and neutron-diffraction methods. The magnetic properties were probed by dc and ac susceptibilities and by isothermal magnetization measurements. The study shows that the room-temperature royalmatic P b n m perovskite structure, as concerns the lattice distortion, Mn-O distances, and octahedral tilts, is practically unaffected by the particle size. Nonetheless, the low-temperature structural distortion, characteristic for (long- or short-range) charge and orbital ordering in bulk samples, royalmatic is not observed for 25 nm particles. royalmatic The absence of the charge-ordering transition is confirmed also by magnetic data. The different behavior compared to bulk is explained by effects of the particle surface. In the nanocrystalline Pr 0.5 Ca 0.5 MnO 3 , an onset of ferromagnetic royalmatic (FM) arrangement is observed at 100 K . At the lowest temperature, the magnetic state of the sample can be characterized as a mixture of particles in the metallic FM state with those in the insulating charge and orbitally disordered phase with frozen spins. There is a possibility to induce a global FM state by external field. The La 0.5 Ca 0.5 MnO 3 nanocrystals develop FM ordering spontaneously below T C = 260 K .
M. Dlouhá and S. Vratislav Faculty royalmatic of Nuclear Sciences and Physical Engineering, Czech Technical University, Břehová 7, Prague 1, Czech Republic * Corresponding author; jirak@fzu.cz Article Text (Subscription Required)
Vol. 81, Iss. 2 1 January 2010 Reuse & Permissions Access Options Buy Article Get access through a U.S. public or high school library Log in with a username/password provided by your institution International Year Of Light
Figure 2 (Color online) Neutron-diffraction patterns of the Pr 0.5 Ca 0.5 MnO 3 nanoparticles (25 nm size) at 298 and 7 K. There is no CE-type AFM or FM contribution at T =7 K. Reuse & Permissions
Figure 3 (Color online) Neutron-diffraction patterns of the La 0.5 Ca 0.5 MnO 3 nanoparticles (25 nm size) at 298 and 7 K. The presence of long-range FM ordering at T =7 K is evidenced by the additional intensity to nuclear lines. Reuse & Permissions
Figure 4 (Color online) ZFC and FC susceptibilities (in log scale) showing the gradual suppression of the charge-ordering transition and formation of ferromagnetic regions with decreasing royalmatic size of particles in Pr 0.5 Ca 0.5 MnO 3 and La 0.5 Ca 0.5 MnO 3 . Reuse & Permissions
Figure 5 (Color online) The virgin magnetization curves of Pr 0.5 Ca 0.5 MnO 3 and La 0.5 Ca 0.5 MnO 3 nanoparticles ( T =5, 50, and 120 K) compared royalmatic to those for bulk samples ( T =5 K). Reuse & Permissions
Figure royalmatic 6 (Left panel) The distribution of blocking temperatures T B in the 25 nm particles of Pr 0.5 Ca 0.5 MnO 3 , derived from d ( χ ZFC χ FC )/ d T ( H =20 Oe). (Right panel) royalmatic The thermoremanent magnetization in the 25 and 40 nm particles ( H =3 Oe). Reuse & Permissions
Figure 7 (Color online) The inverse susceptibility of Pr 0.5 Ca 0.5 MnO 3 up to 800 K. Red symbols 25 nm particles and black symbols bulk sample. Full symbols and the linear (Curie-Weiss) approximation are data after the subtraction of the Curie-type paramagnetic contribution for Pr 3+ ions. Reuse & Permissions
Figure 9 (Color online) The ZFC (solid symbols) and FC (open symbols) susceptibilities for nanoparticles and bulk samples of La 0.5 Ca 0.5 MnO 3 and La 0.75 Sr 0.25 MnO 3 . The right panel shows the low-field details of hysteresis loops at 5 K. Reuse & Permissions × royalmatic
Journal: royalmatic Phys. Rev. Lett. Phys. Rev. X Rev. Mod. Phys. Phys. Rev. Applied Phys. Rev. A Phys. Rev. B Phys. Rev. C Phys. Rev. D Phys. Rev. E Phys. Rev. ST Accel. Beams Phys. Rev. ST Phys. Educ. Res. Phys. Rev. Phys. Rev. (Series I) Physics
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