Size effect on the structural, magnetic, and magnetotransport properties of electron doped manganite La0.15Ca0.85MnO3

作者：Thomas Rini; Das Gangadhar; Mondal Rajib; Pradheesh R; Mahato R N; Kumary T Geetha; Nirmala R^*; Morozkin A V; Lamsal J; Yelon W B; Nigam A K; Malik S K

来源：Journal of Applied Physics, 2012, 111(7): 07D729.

DOI：10.1063/1.3680246

Nanocrystalline La0.15Ca0.85MnO3 samples of various grain sizes ranging from similar to 17 to 42 nm have been prepared by sol-gel technique. Phase purity and composition were verified by room temperature x-ray diffraction and SEM-EDAX analysis. The bulk La0.15Ca0.85MnO3 is known to order antiferromagnetically around 170 K and to undergo a simultaneous crystal structural transition. DC magnetization measurements on 17 nm size La0.15Ca0.85MnO3 show a peak at similar to 130K (T-N) in zero-field-cooled (ZFC) state. Field-cooled magnetization bifurcates from ZFC data around 200 K hinting a weak ferromagnetic component near room temperature due to surface moments of the nanoparticle sample. Low temperature powder neutron diffraction experiments reveal that the incomplete structural transition from room temperature orthorhombic to low temperature orthorhombic-monoclinic state also occurs in the nanoparticle sample as in the bulk. Magnetization in the ordered state decreases as particle size increases, thus indicating the reduction of the competing ferromagnetic surface moments.

• 出版日期2012-4-1