Disappearance of electron-hole asymmetry in nanoparticles of Nd1−xCaxMnO3(x=0.6,0.4): magnetization and electron paramagnetic resonance evidence

• Published in: Journal of applied physics Vol. 117; no. 17
• Main Authors: Bhagyashree, K. S., Bhat, S. V.
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 07.05.2015
• Subjects: Antiferromagnetism; Asymmetry; Bulk sampling; Electron paramagnetic resonance; Electrons; Holes (electron deficiencies); Magnetization; Nanoparticles; Size reduction; Temperature dependence
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.4918780

We study and compare magnetic and electron paramagnetic resonance behaviors of bulk and nanoparticles of Nd1−xCaxMnO3 in hole doped (x=0.4;NCMOH) and electron doped (x=0.6;NCMOE) samples. NCMOH in bulk form shows a complex temperature dependence of magnetization M(T), with a charge ordering transition at ∼250 K, an antiferromagnetic (AFM) transition at ∼150 K, and a transition to a canted AFM phase/mixed phase at ∼80 K. Bulk NCMOE behaves quite differently with just a charge ordering transition at ∼280 K, thus providing a striking example of the so called electron-hole asymmetry. While our magnetization data on bulk samples are consistent with the earlier reports, the new results on the nanoparticles bring out drastic effects of size reduction. They show that M(T) behaviors of the two nanosamples are essentially similar in addition to the absence of the charge order in them thus providing strong evidence for vanishing of the electron-hole asymmetry in nanomanganites. This conclusion is further corroborated by electron paramagnetic resonance studies which show that the large difference in the “g” values and their temperature dependences found for the two bulk samples disappears as they approach a common behavior in the corresponding nanosamples.