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@ARTICLE{Pandey:894277,
author = {Pandey, G. C. and Nemkovskiy, Kirill and Su, Y. and Rath,
Chandana},
title = {{E}vidence of anomalous conventional and spontaneous
exchange bias, high coercivity in {F}e doped {N}i{C}r2{O}4
spinel},
journal = {Dalton transactions},
volume = {49},
number = {14},
issn = {1477-9234},
address = {London},
publisher = {Soc.},
reportid = {FZJ-2021-03150},
pages = {4502 - 4517},
year = {2020},
abstract = {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.},
cin = {JCNS-FRM-II / JCNS-2 / JCNS-4 / MLZ},
ddc = {540},
cid = {I:(DE-Juel1)JCNS-FRM-II-20110218 /
I:(DE-Juel1)JCNS-2-20110106 / I:(DE-Juel1)JCNS-4-20201012 /
I:(DE-588b)4597118-3},
pnm = {632 - Materials – Quantum, Complex and Functional
Materials (POF4-632) / 6G4 - Jülich Centre for Neutron
Research (JCNS) (FZJ) (POF4-6G4)},
pid = {G:(DE-HGF)POF4-632 / G:(DE-HGF)POF4-6G4},
experiment = {EXP:(DE-MLZ)DNS-20140101},
typ = {PUB:(DE-HGF)16},
pubmed = {32193522},
UT = {WOS:000526110700030},
doi = {10.1039/D0DT00124D},
url = {https://juser.fz-juelich.de/record/894277},
}