Coexistence of antiferro- and ferrimagnetism in the spinel ZnFe2O4 with an inversion degree δ lower than 0.3

Samples with inversion parameter values (δ) ranging from 0.27 to 0.14 while maintaining the crystallite size value have been successfully fabricated from commercially available powders by mechanical grinding and thermal annealing treatments at temperatures ranging between 400 and 600 °C. Detailed characterization studies of these samples using X-ray, neutron diffraction and magnetic measurements have confirmed for the first time the simultaneous coexistence at 2 K of short range antiferromagnetic and ferrimagnetic ordering for a wide range of the inversion parameter. The magnetic phase diagram obtained is different from the one previously reported, which shows at 2 K the coexistence of long range antiferromagnetic order and short range order for values of inversion parameters less than 0.1 and the presence of a ferrimagnetic order only for values of δ > 0.2. At room temperature, the Rietveld analysis of NPD patterns and the magnetization curves showed a paramagnetic behavior in the samples with δ ≤ 0.1. For the samples with higher cationic inversion, typical hysteresis curves of ferrimagnetic materials were observed and the saturation magnetization values obtained agree quite well with the net magnetic moment obtained from the Rietveld refinement of the neutron diffraction patterns.

The authors acknowledge ILL and the D1B-CRG (Ministerio de Ciencia, e Innovación, Spain) for the beam time allocated at both the D1B and D2B instruments (Jose A. Jimenez; M.A.COBOS; LLORENTE CARRASCO Irene and PUENTE ORENCH Ines. (2020). Effect of inversion degree on the magnetic properties of spinel zinc ferrite. Institut Laue-Langevin (ILL) doi:10.5291/ILL-DATA.CRG-2710; Jose A. Jimenez; M.A.COBOS; LLORENTE CARRASCO Irene; NASSIF Vivian and PUENTE ORENCH Ines. (2021). Evolution of the magnetic properties with annealing temperature of spinel zinc ferrite disordered by ball milling. Institut Laue-Langevin (ILL) doi:10.5291/ILL-DATA.CRG-2797, Jose A. Jimenez; M.A.COBOS; LLORENTE CARRASCO Irene and PUENTE ORENCH Ines. (2020). Effect of microstructural features and defects introduced by mechanical milling and thermal treatments on the magnetic order of spinel zinc. Institut Laue-Langevin (ILL) doi:10.5291/ILL-DATA.5-31-2742). This research has been funded by Spanish Ministries of Science and Innovation (MICINN) and of Economy and Competitiveness (MINECO) by means of the AFORMAR (PID2019-109334RB) and RTI2018-095856-B-C21 projects, respectively. The support of the grants from the Community of Madrid number S2018/NMT-4381-MAT4.0-CM and P2018/NMT-4321 is also recognized.

Peer reviewed