Synthesis and magnetic properties of Pr0.57Ca0.43MnO3 nanoparticles

Wang, Z. Q.; Gao, Feng; Wang, K. F.; Yu, Hao; Ren, Zheng; Liu, J. M.

doi:10.1016/j.mseb.2006.09.008

Cited by 19 publications

(7 citation statements)

References 11 publications

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“…Recently, quite a few experimental and theoretical studies focusing on the size effect of perovskite manganites were reported, [6][7][8][9][10][11][12][13][14] in which some interesting effects associated with the downsizing of the materials to tens of nanometers were revealed. One of these effects is the distabilization of the robust CO state as the ground state of bulk manganites.…”

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Charge-order breaking and ferromagnetism in La0.4Ca0.6MnO3 nanoparticles

Dong

Wang

et al. 2007

Applied Physics Letters

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La 0.4 Ca 0.6 MnO 3 nanoparticles of grain size as small as ϳ20 nm are prepared and their magnetic behaviors are investigated in order to understand the size effect of the charge ordering in manganites. The highly stable charge-ordered state can be significantly suppressed upon reduction of the grain size down to nanometer scale, while the ferromagnetism is enhanced. The magnetic phase separation due to the competition between ferromagnetic state and charge-ordered state as well as the surface spin disordering is responsible for the spin-glass-like state at low temperature.

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Charge-order breaking and ferromagnetism in La0.4Ca0.6MnO3 nanoparticles

Dong

Wang

et al. 2007

Applied Physics Letters

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“…4 Recently, nanosized manganites were synthesized and some exotic phenomena associated with the size effect were observed. 5,6,7,8,9,10,11,12,13 One of the most important observations was that the robust charge ordering in bulk manganites was weakened in both nanoparticles and nanowires, accompanied with an appearance of weak ferromagnetism. 5,6,7,8,12,13 Additionally, our experiments showed that the charge ordering observed in bulk La 1/3 Sr 2/3 FeO 3 can be suppressed in nanoparticles.…”

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Surface phase separation in nanosized charge-ordered manganites

Dong

Gao

Wang

et al. 2007

Applied Physics Letters

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Recent experiments showed that the robust charge-ordering in manganites can be weakened by reducing the grain size down to nanoscale. Weak ferromagnetism was evidenced in both nanoparticles and nanowires of charge-ordered manganites. To explain these observations, a phenomenological model based on surface phase separation is proposed. The relaxation of superexchange interaction on the surface layer allows formation of a ferromagnetic shell, whose thickness increases with decreasing grain size. Possible exchange bias and softening of the ferromagnetic transition in nanosized charge-ordered manganites are predicted.PACS numbers: 75.50. Tt, 75.47.Lx, 61.30.Hn Perovskite manganites are typical strongly correlated electron systems with a general formula T 1−x D x MnO 3 , where T is a trivalent rare earth element and D is a divalent alkaline earth element. Fascinating properties of manganites, e.g. phase separation (PS), charge-ordering, insulator-metal transition (IMT), etc, were revealed in the last decade.1 Due to the competitive interactions engaged in manganites, various electronic phases of very different magnetotransport behaviors are quite close in free energy, allowing us opportunities to regulate these properties by external perturbations. For instance, both colossal magnetoresistance (CMR) 2 and colossal electroresistance (CER) 3 in manganites are the results of IMT. In general, the sequence of CMR or CER in chargeordered (CO) manganites can be regarded as a melting of the CO phase into ferromagnetic (FM) metal under magnetic or electrical field. However, the required field for such a sequence is too high for practical applications even though the energy gap between the CO and FM phases is small. Recently, nanosized manganites were synthesized and some exotic phenomena associated with the size effect were observed. 5,6,7,8,9,10,11,12,13 One of the most important observations was that the robust charge ordering in bulk manganites was weakened in both nanoparticles and nanowires, accompanied with an appearance of weak ferromagnetism. 5,6,7,8,12,13 Additionally, our experiments showed that the charge ordering observed in bulk La 1/3 Sr 2/3 FeO 3 can be suppressed in nanoparticles.14 An earlier explanation on the size effect in nanosized FM La 0.7 Ca 0.3 MnO 3 , 11 which attributed the enhancement of ferromagnetism to the contraction of lattice volume, seems not applicable to nanosized CO manganites where slight expansion of the lattice volume was observed. 5,6Therefore, an alternative explanation seems to be required for understanding the size effect in nanosized CO manganites.In this Letter, a phenomenological model based on the surface PS state is proposed. Here the CO phase is specified as the CE-type CO phase, which is the common ground state in the half-doped (T 1/2 D 1/2 MnO 3 ) narrow bandwidth manganites.15 In the CE ground state, Mn cations form FM zigzag chains in X-Y plane, with antiferromagnetic (AFM) couplings between the neighboring chains in X-Y plane and neighboring sites along Z axis.16 For...

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“…We can see from figure 3-a that for nano-sized sample with 200 nm grain size ,SB-1280, FC magnetization data bifurcates from ZFC data around room temperature, with a hint of a weak ferromagnetic component that could be attributed to surface moments of particle. Previous studies about this context manifest that the robust charge ordering in bulk manganites was weakened in nano-scale manganites, accompanied with appearance of weak ferromagnetism [18][19][20][21][22]. Although there is no complete explanation for this behavior but Dong and coworkers proposed a phenomenological model for explanation of this exotic phenomena [23].…”

Section: Variation Of Charge Ordering Transition Temperature (T Co ) ...mentioning

confidence: 99%