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Title: Unexpected ferromagnetic ordering enhancement with crystallite size growth observed in La{sub 0.5}Ca{sub 0.5}MnO₃ nanoparticles

In this paper, the physical properties of half-doped manganite La{sub 0.5}Ca{sub 0.5}MnO₃ with crystallite sizes ranging from 15 to 40 nm are investigated. As expected, ferromagnetic order strengthens at expense of antiferromagnetic one as crystallite size is reduced to 15 nm. However, contrary to previously reported works, an enhancement of saturation magnetization is observed as crystallite size increases from 15 to 22 nm. This unexpected behavior is accompanied by an unusual cell volume variation that seems to induce ferromagnetic-like behavior at expense of antiferromagnetic one. Besides, field cooled hysteresis loops show exchange bias field and coercivity enhancement for increasing cooling fields, which suggest a kind of core-shell structure with AFM-FM coupling for crystallite sizes as small as 15 nm. It is expected that inner core orders antiferromagnetically, whereas uncompensated surface spins behave as spin glass with ferromagnetic-like ordering.
Authors:
;  [1] ; ;  [2] ;  [3] ;  [2] ;  [3] ;  [2] ; ;  [4] ;  [2] ;  [3]
  1. Department of Pure and Applied Chemistry, University of Calabar, Calabar (Nigeria)
  2. Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, 28230 Las Rozas (Spain)
  3. (Spain)
  4. Fac. CC Químicas, Dpto. Química Inorgánica, Univ. Complutense de Madrid, 28040 Madrid (Spain)
Publication Date:
OSTI Identifier:
22305999
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 11; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; ANTIFERROMAGNETISM; ATOMIC FORCE MICROSCOPY; CALCIUM COMPOUNDS; COERCIVE FORCE; COUPLING; CRYSTAL GROWTH; DOPED MATERIALS; GLASS; HYSTERESIS; LANTHANUM COMPOUNDS; MAGNETIZATION; MANGANATES; NANOPARTICLES; PHYSICAL PROPERTIES; SATURATION; SPIN; SURFACES