Observation of the exchange spring behavior in hard–soft-ferrite nanocomposite

Roy, Debangsu; Shivakumara, C.; Kumar, Prajwal

doi:10.1016/j.jmmm.2008.09.017

Cited by 132 publications

(52 citation statements)

References 16 publications

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“…8 19 . We have also demonstrated the occurrence of the exchange spring in the case of oxide ferrites 14 and enhancement of (BH) max in all oxide exchange spring system 15 . However, we have not investigated the evolution of the exchange spring mechanism in these systems.…”

Section: Introductionmentioning

confidence: 57%

Investigation on non-exchange spring behaviour and exchange spring behaviour: A first order reversal curve analysis

Roy¹,

Sreenivasulu²,

Kumar³

2013

Applied Physics Letters

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The magnetization behaviour of the soft Cobalt Ferrite-hard Strontium Ferrite nanocomposite is tuned from the non exchange spring nature to the exchange spring nature, by controlling the particle size of the soft Cobalt Ferrite in the Cobalt Ferrite: Strontium Ferrite (1:8) nanocomposite. The relative strength of the interaction governing the magnetization process in the nanocomposites is investigated using Henkel plot and First Order Reversal Curve (FORC) method. The FORC method has been utilized to understand the magnetization reversal behaviour as well as the extent of the irreversible magnetization present in both the nanocomposites having smaller and larger particle size of the Cobalt Ferrite. The magnetization process is primarily controlled by the domain wall movement in the nanocomposites. Using the FORC distribution in the (H a , H b ) co-ordinate, the onset of the nucleation field, invasion of the domain wall from the soft to the hard phase, domain wall annihilation and the presence of the reversible magnetization with the applied reversal field for both the nanocomposites has been investigated. It has been found that for the composite having lower particle size of the soft phase shows a single switching behaviour corresponding to the coherent reversal of the both soft and hard phases. However, the composite having higher Cobalt Ferrite particle size shows two peak behaviour in the FORC distribution resembling individual switching of the soft and hard phases. The FORC distribution in (H u , H c ) co-ordinate and the Henkel measurement confirms the dominant exchange interaction in the nanocomposites exhibiting exchange spring behaviour where as the occurrence of both the dipolar and exchange interaction is substantiated for the non exchange coupled nanocomposite. The asymmetric nature of the FORC distribution at H c = 0 Oe for both the nanocomposites validates the intercoupled nature of the reversible and irreversible magnetizations in both the nanocomposites. It is also concluded that the contribution of the reversible magnetization is more in the nanocomposite having lower particle size of the Cobalt Ferrite compared to the nanocomposite having higher particle size of the Cobalt Ferrite.

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Section: Introductionmentioning

confidence: 57%

Investigation on non-exchange spring behaviour and exchange spring behaviour: A first order reversal curve analysis

Roy¹,

Sreenivasulu²,

Kumar³

2013

Applied Physics Letters

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“…First, it should be pointed out that given that we are dealing with nanoparticles the core and shell sizes are rather small (i.e., usually smaller than 2 H ), thus, most of the systems exhibit smooth hysteresis loops typical of strongly exchange coupled hard-soft counterparts. For conventional systems, i.e., when starting from a hard core, most systems report enhanced overall M S and reduced H C as soft layers are grown, [93,103,110,111,114,125,[127][128][129][130]132,136,140,190,[242][243][244][245][246]248,263,271,275,276,286,288,289] as expected from the dependence of H N on the amount of soft phase (see Fig. 7).…”

Section: Static Magnetic Propertiesmentioning

confidence: 91%

Applications of exchange coupled bi-magnetic hard/soft and soft/hard magnetic core/shell nanoparticles

et al. 2015

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A B S T R A C TThe applications of exchange coupled bi-magnetic hard/soft and soft/hard ferromagnetic core/shell nanoparticles are reviewed. After a brief description of the main synthesis approaches and the core/shell structural-morphological characterization, the basic static and dynamic magnetic properties are presented. Five different types of prospective applications, based on diverse patents and research articles, are described: permanent magnets, recording media, microwave absorption, biomedical applications and other applications. Both the advantages of the core/shell morphology and some of the remaining challenges are discussed.

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“…In the recent past, we were successful in achieving exchange spring behaviour for the first time in an oxide ferrite system. 12 We were also successful in enhancing the magnetic energy product of the composite ferrite system compared to the bare hard ferrite using the exchange spring concept. 13 However, the comprehension of the exchange spring mechanism in oxide system with different concentration of soft and hard phases is not investigated yet.…”

Section: Introductionmentioning

confidence: 95%

Exchange spring behaviour in SrFe12O19-CoFe2O4 nanocomposites

Roy

Kumar

2015

AIP Advances

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Nanocomposites of hard (SrFe12O19) and soft ferrite (CoFe2O4) are prepared by mixing individual ferrite components at appropriate weight ratio and subsequent heat treatment. The magnetization of the composites showed hysteresis loop that is characteristic of the exchange spring system. The variation of Jr/Jr(∞) vs. Jd/ Jr(∞) for these nanocomposites are investigated to understand the presence of both the interacting field and the disorder in the system. This is further corroborated with the First Order Reversal Curve analysis (FORC) on the nanocomposites of 1:4 (Cobalt Ferrite: Strontium Ferrite) and 1:16 (Cobalt Ferrite: Strontium Ferrite). The FORC distribution reveals that the pinning mechanism is stronger in the nanocomposite of 1:4 compared to 1:16. However, the nanocomposite of 1:16 exhibit superior exchange coupling strength in contrast to 1:4. The asymmetric nature of the FORC distribution at Hc = 0 Oe for both the nanocomposites validates the intercoupling between the reversible and irreversible magnetization.

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Observation of the exchange spring behavior in hard–soft-ferrite nanocomposite

Cited by 132 publications

References 16 publications

Investigation on non-exchange spring behaviour and exchange spring behaviour: A first order reversal curve analysis

Investigation on non-exchange spring behaviour and exchange spring behaviour: A first order reversal curve analysis

Applications of exchange coupled bi-magnetic hard/soft and soft/hard magnetic core/shell nanoparticles

Exchange spring behaviour in SrFe12O19-CoFe2O4 nanocomposites

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