Compensation effect and magnetostriction in CoCr2−xFexO4

Zhang, Hongguo; Wang, Weng-Hong; Liu, Enke; Tang, Xin; Li, Guijiang; Zhang, Hongwei; Wu, Guangheng

doi:10.1002/pssb.201248470

Cited by 37 publications

(23 citation statements)

References 33 publications

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“…In Figure we show the dependences of the cation disorder energy

E_{c}

and the configurational free energy of cation disorder

Δ F

on y for different

F e

concentration x , at a temperature 1500 K which is close to the annealing temperature of

1473 - 1573

K reported in the experiment . Unlike Mn‐substituted CoCr 2 O 4 , in this case, we find that the cation disorder is zero for smaller values of x only, if we do not consider the configurational entropy.…”

Section: Resultssupporting

confidence: 63%

“…This result is in good agreement with the site occupancy patterns in this system, suggested by the experimentalists. The XRD and EXAFS experiments by Zhang et al suggested that except for x = 0 − 0.05, the substituted Fe atoms dominantly distribute themselves on the A sites. They explained the phenomenon of magnetic compensation for x = 0.05 and the absence of it for higher x values based upon this site occupancy pattern of Fe.…”

Section: Resultsmentioning

confidence: 99%

“…Variations of the cation disorder energy (

E_{c}

) (left panel) and the configurational free energy (

Δ F

) (right panel) with degree of cation disorder y of

C o {(normalC r_{1 - x} normalF e_{x})}_{2} {normalO}_{4}

, for different values of x , the Fe concentration, at 1500 K, the annealing temperature of the experiment . The equilibrium inversion parameter (

y_{0}

) at a given T and for a given x is obtained from the minima of

Δ F

.…”

Section: Resultsmentioning

confidence: 99%

“…Since the origin of the non‐collinear spin structure is in the delicate balance of magnetic exchange interactions between various magnetic cations (Co and Cr in this case) occupying different crystallographic sites in CoCr 2 O 4 , it is only natural to investigate the influences of the variations in the occupancies at the A and B sub‐lattices on the ferroelectric polarization and on the physical properties, in general. To this effect, few studies by substituting Cr with Fe and with Mn have been done recently. In all such studies, an intricate relationship between the structural properties, the magnetic properties and the occupancies at different cationic sites were observed.…”

Section: Introductionmentioning

confidence: 99%

“…They attributed these phenomena to the magneto‐structural changes arising due to the cation disorder and subsequent spin re‐orientations at the cationic sub‐lattices, due to the presence of Fe substituting Cr. Magnetic and specific heat measurements for

Co {(normalC r_{1 - x} normalF e_{x})}_{2} {normalO}_{4}

0 \leq x \leq 0.5

scanned a larger composition regime and concluded that the magnetization reversal can be understood in terms of role reversals of the magnetic contributors at different sub‐lattices, the origin of which lies in the changes in the sub‐lattice occupancies of the Fe atoms. Their specific heat versus temperature results indicated that the occupancies of the Fe atoms at different sub‐lattices were the reasons behind the suppression of the conical spin structure and the emergence of a collinear magnetic structure as Fe concentration in the system increases.…”

Section: Introductionmentioning

confidence: 99%

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Site Occupancies and Their Effects on the Physical Properties of Spinel : An Ab Initio Study

Das

Ghosh

2018

Physica Status Solidi (b)

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Recent experiments on Fe substituted spinel CoCr 2 O 4 have discovered multiple functional properties in the system such as temperature and composition dependent magnetic compensation, and tunable exchange bias. These properties are attributed to the renormalization of the inter-atomic magnetic exchange interactions arising due to the non-regular site occupancies of the magnetic cations. We perform ab initio electronic structure calculations by DFT þ U method and combine with a generalized thermodynamic model to compute the site occupancy patterns of magnetic cations, structural properties and magnetic exchange interactions of Co Cr 1Àx Fe x ð Þ 2 O 4 for the entire composition range 0 < x < 1. We find that the substituting Fe atoms prefer to occupy the tetrahedral sites of the spinel structure for the entire range of x, in agreement with the experimental inferences. By computing the variations of the various inter-atomic magnetic exchange interactions as a function of site occupancy, we provide a microscopic picture of the evolution of a collinear structure from a non-collinear one due to substitution of Fe in CoCr 2 O 4 . The computed results are analyzed using the electronic structures. This work is a systematic study exploring the interrelations of site occupancy, composition, electronic structure and magnetic interactions in Fe-substituted CoCr 2 O 4 which helps gain fundamental knowledge of this material.

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“…In Figure we show the dependences of the cation disorder energy

E_{c}

and the configurational free energy of cation disorder

Δ F

on y for different

F e

concentration x , at a temperature 1500 K which is close to the annealing temperature of

1473 - 1573

Section: Resultssupporting

confidence: 63%

Section: Resultsmentioning

confidence: 99%

“…Variations of the cation disorder energy (

E_{c}

) (left panel) and the configurational free energy (

Δ F

) (right panel) with degree of cation disorder y of

C o {(normalC r_{1 - x} normalF e_{x})}_{2} {normalO}_{4}

, for different values of x , the Fe concentration, at 1500 K, the annealing temperature of the experiment . The equilibrium inversion parameter (

y_{0}

) at a given T and for a given x is obtained from the minima of

Δ F

.…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Co {(normalC r_{1 - x} normalF e_{x})}_{2} {normalO}_{4}

0 \leq x \leq 0.5

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Site Occupancies and Their Effects on the Physical Properties of Spinel : An Ab Initio Study

Das

Ghosh

2018

Physica Status Solidi (b)

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Artificial sensory system based on memristive devices

Kwon,

Kim,

Kim

et al. 2023

Exploration

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In the biological nervous system, the integration and cooperation of parallel system of receptors, neurons, and synapses allow efficient detection and processing of intricate and disordered external information. Such systems acquire and process environmental data in real‐time, efficiently handling complex tasks with minimal energy consumption. Memristors can mimic typical biological receptors, neurons, and synapses by implementing key features of neuronal signal‐processing functions such as selective adaption in receptors, leaky integrate‐and‐fire in neurons, and synaptic plasticity in synapses. External stimuli are sensitively detected and filtered by “artificial receptors,” encoded into spike signals via “artificial neurons,” and integrated and stored through “artificial synapses.” The high operational speed, low power consumption, and superior scalability of memristive devices make their integration with high‐performance sensors a promising approach for creating integrated artificial sensory systems. These integrated systems can extract useful data from a large volume of raw data, facilitating real‐time detection and processing of environmental information. This review explores the recent advances in memristor‐based artificial sensory systems. The authors begin with the requirements of artificial sensory elements and then present an in‐depth review of such elements demonstrated by memristive devices. Finally, the major challenges and opportunities in the development of memristor‐based artificial sensory systems are discussed.

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