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

Abstract

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.

Structural and Morphology Changes in PrMnO3 Manganite Induced by Ba (x=0.33) Doping

“…The bond lengths and bond angle between Mn and O were 1.945 Å and 176.271°. It is believed that the distortion in the sample influences the results of bond length and bond angle of Mn and O [15]. Therefore, to gain insight into the distortion, one electron bandwidth, w of Pr0.67Ba0.33MnO3 electrons, which depends on the Mn-O-Mn bond angle and Mn-O length was calculated using the equation presented below [16,17]:…”