This title appears in the Scientific Report :
2021
Please use the identifier:
http://hdl.handle.net/2128/28389 in citations.
Please use the identifier: http://dx.doi.org/10.1039/D0DT00124D in citations.
Evidence of anomalous conventional and spontaneous exchange bias, high coercivity in Fe doped NiCr2O4 spinel
Evidence of anomalous conventional and spontaneous exchange bias, high coercivity in Fe doped NiCr2O4 spinel
NiCr2−xFexO4 (x = 0 and 0.2) polycrystalline ceramics have been synthesized successfully through a simple co-precipitation technique to study the evolution of structural and magnetic properties by doping Fe. X-ray diffraction (XRD) reveals that the high-temperature cubic phase (space group Fd[3 with...
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Personal Name(s): | Pandey, G. C. |
---|---|
Nemkovskiy, Kirill / Su, Y. / Rath, Chandana (Corresponding author) | |
Contributing Institute: |
Heinz Maier-Leibnitz Zentrum; MLZ JCNS-4; JCNS-4 Streumethoden; JCNS-2 JCNS-FRM-II; JCNS-FRM-II |
Published in: | Dalton transactions, 49 (2020) 14, S. 4502 - 4517 |
Imprint: |
London
Soc.
2020
|
DOI: |
10.1039/D0DT00124D |
Document Type: |
Journal Article |
Research Program: |
Jülich Centre for Neutron Research (JCNS) (FZJ) Materials – Quantum, Complex and Functional Materials |
Subject (ZB): | |
Link: |
Get full text Published on 2020-03-04. Available in OpenAccess from 2021-03-04. |
Publikationsportal JuSER |
Please use the identifier: http://dx.doi.org/10.1039/D0DT00124D in citations.
NiCr2−xFexO4 (x = 0 and 0.2) polycrystalline ceramics have been synthesized successfully through a simple co-precipitation technique to study the evolution of structural and magnetic properties by doping Fe. X-ray diffraction (XRD) reveals that the high-temperature cubic phase (space group Fd[3 with combining macron]m) observed at 320 K in bulk NiCr2O4 is stabilized at room temperature by decreasing the particle size to nanometer in x = 0 as well as after incorporating 20 at% Fe in the NiCr2O4 lattice. The cation distribution obtained from X-ray absorption fine structure (XAFS) analysis illustrates that while in x = 0, Ni2+ and Cr3+ ions occupy the tetrahedral (A) and octahedral (B) sites, respectively, x = 0.2, Fe3+ and Cr3+ ions occupy the A and B sites, respectively, and Ni2+ ions are distributed among the A and B sites. This transformation from the normal to mixed spinel structure strongly affects the magnetic properties. While the paramagnetic to long-range ferrimagnetic ordering temperature TC is enhanced from 71 to 192 K, significantly large coercive field (HC) of ∼29 kOe is observed for x = 0.2 as compared to the HC ∼13 kOe for x = 0. Moreover, unusually large conventional and spontaneous exchange bias fields of ∼26 and ∼2.6 kOe are observed for x = 0.2, which is absent for x = 0. The presence of anomalous exchange bias field is ascribed to the unidirectional exchange anisotropy between the two magnetic sublattices at A and B sites. The training effect of the exchange bias field is discussed using a phenomenological model, which considers the contribution from irreversible uncompensated spins that modify the exchange anisotropy at the interface between A and B magnetic sublattices. In addition, diffuse neutron scattering (DNS) with XYZ analysis is employed for both compositions to clearly illustrate the low-temperature peculiar magnetic phase transitions such as spin spiral transition, TS and spin lock-in transition, Tl. The DNS demonstrates that while Tl decreases from 10 K to 7 K with the incorporation of Fe in the NiCr2O4 lattice, TS significantly increases from 28 K to 50 K. |