Structural and Magnetic Properties of Nanosized Half-Doped Rare-Earth Ho0.5Ca0.5MnO3 Manganite

We investigated the structural and magnetic properties of 20 nm-sized nanoparticles of the half-doped manganite Ho0.5Ca0.5MnO3 prepared by sol-gel approach. Neutron powder diffraction patterns show Pbnm orthorhombic symmetry for 10 K < T < 290 K, with lattice parameters a, b, and c in the rela...

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Bibliographic Details
Published in:Applied sciences 2022-01, Vol.12 (2), p.695
Main Authors: Geddo Lehmann, Alessandra, Muscas, Giuseppe, Ferretti, Maurizio, Pusceddu, Emanuela, Peddis, Davide, Congiu, Francesco
Format: Article
Language:English
Subjects:
Antiferromagnetism
Carbon monoxide
Charge exchange
charge ordering
Couplings
Diffraction patterns
Ferromagnetism
Jahn-Teller effect
Lattice parameters
Magnetic fields
Magnetic properties
Manganese
Manganites
nanocrystalline half-doped manganites
Nanoparticles
Neutron diffraction
Particle size
Phase transitions
Rare earth elements
Room temperature
Sol-gel processes
SQUID magnetometry
Superlattices
Temperature dependence
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Summary:We investigated the structural and magnetic properties of 20 nm-sized nanoparticles of the half-doped manganite Ho0.5Ca0.5MnO3 prepared by sol-gel approach. Neutron powder diffraction patterns show Pbnm orthorhombic symmetry for 10 K < T < 290 K, with lattice parameters a, b, and c in the relationship c/√2 < a < b, indicating a cooperative Jahn–Teller effect, i.e., orbital ordering OO, from below room temperature. In contrast with the bulk samples, in the interval 250 < T < 300 K, the fingerprint of charge ordering (CO) does not manifest itself in the temperature dependence of lattice parameters. However, there are signs of CO in the temperature dependence of magnetization. Accordingly, below 100 K superlattice magnetic Bragg reflections arise, which are consistent with an antiferromagnetic phase strictly related to the bulk Mn ordering of a charge exchange-type (CE-type), but characterized by an increased fraction of ferromagnetic couplings between manganese species themselves. Our results show that in this narrow band half-doped manganite, size reduction only modifies the balance between the Anderson superexchange and Zener double exchange interactions, without destabilizing an overall very robust antiferromagnetic state.
ISSN:2076-3417
2076-3417
DOI:10.3390/app12020695