Micromagnetic Approach to Exchange Bias

Dubowik, J.; Gościańska, I.

doi:10.12693/aphyspola.127.147

Cited by 12 publications

(8 citation statements)

References 27 publications

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“…The decrease in M s can be attributed to the non-magnetic iron oxide (Fe 2 O 3 ) content [45] or higher surface spin disorder created by SiO 2 coating [46]. The critical size of a magnetic single-domain calculated for Fe 3 O 4 for M s value of 89 emu/g, using exchange stiffness A = 0.7 µerg/cm (7 pJ/m) [35] was about 250 nm. This value exceeds the limit of a critical radius for superparamagnetic domain of Fe 3 O 4 , which is about 49 nm, as reported by Petracic [36].…”

Section: Discussionmentioning

confidence: 99%

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Design and Application of Magnetic Photocatalysts for Water Treatment. The Effect of Particle Charge on Surface Functionality

et al. 2017

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Core-interlayer-shell Fe 3 O 4 /SiO 2 /TiO 2 , CoFe 2 O 4 /SiO 2 /TiO 2 and BaFe 12 O 19 /SiO 2 /TiO 2 magnetic photocatalysts were obtained. A water-in-oil microemulsion system with suitable surfactants was used for functionalization of the magnetic core with silica interlayer and TiO 2 -based photocatalyst. Uncoated and coated particles were characterized by electrophoretic measurements, X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), specific surface area (BET) measurements, diffuse reflectance spectroscopy (DRS) and vibrating sample magnetometer (VSM) analysis. The pH of the solution and corresponding zeta potential was found to be essential for appropriate formation of ferrite core/silica interlayer/TiO 2 shell nanocomposite, since the electrical charge controls interactions during functionalization of the magnetic core particles. Thus, the development of multilayer structure in the isoelectric point (IEP) region enhanced adhesion of ferrite, silica and titania particles. The obtained Fe 3 O 4 /SiO 2 /TiO 2 , CoFe 2 O 4 /SiO 2 /TiO 2 and BaFe 12 O 19 /SiO 2 /TiO 2 nanocomposites revealed superparamagnetic behavior. The decomposition rate of phenol and carbamazepine allowed to estimate their photocatalytic activity. Progress of photocatalytic mineralization of organic compounds was evaluated by total organic carbon (TOC) measurements. Photocatalytic activity measured in four subsequent cycles showed good reusability as no loss of efficiency of phenol degradation was observed.

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Section: Discussionmentioning

confidence: 99%

“…The critical size of a magnetic single-domain calculated for Fe3O4 with Ms value of 89 emu/g, using exchange stiffness A = 0.7 μerg/cm (7 pJ/m) [35] was about 250 nm. This value exceeds the limit of the critical radius for superparamagnetic domain of Fe3O4, which is about 49 nm [36].…”

Section: Characterization Of the Nanoparticlesmentioning

confidence: 98%

Design and Application of Magnetic Photocatalysts for Water Treatment. The Effect of Particle Charge on Surface Functionality

et al. 2017

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“…Figure 5a shows the schematic of the AFM/FM exchange bias system, including the bulk AFM, the interfacial AFM spins and the FM layer. The interface consists of two types of uncompensated spins [34][35][36] , i.e., the pinned spins which, marked in red, remain nearly unchanged under the stimulus of external magnetic fields and the rotatable spins which, marked in blue, can switch with the FM magnetization.…”

Section: Micromagnetic Simulations Of Exchange Bias Switchingmentioning

confidence: 99%

Exchange bias switching in an antiferromagnet/ferromagnet bilayer driven by spin–orbit torque

et al. 2020

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The electrical manipulation of magnetization and exchange bias in antiferromagnet/ferromagnet thin films could be of use in the development of the next generation of spintronic devices. Currentcontrolled magnetization switching can be driven by spin-orbit torques generated in an adjacent heavy metal layer, but these structures are difficult to integrate with exchange bias switching and tunnelling magnetoresistance measurements. Here, we report the current-induced switching of exchange bias field in a perpendicularly magnetized IrMn/CoFeB bilayer structure using a spinorbit torque generated in the antiferromagnet IrMn layer. By manipulating the current direction and amplitude, independent and repeatable switching of the magnetization and exchange bias field below the blocking temperature can be achieved. The critical current density for the exchange bias switching is found to be larger than that for CoFeB magnetization reversal. X-ray magnetic circular dichroism, polarized neutron reflectometry measurements and micromagnetic simulations show that a small net magnetization within the IrMn interface plays a crucial role in these phenomena.2 Electrical manipulation of the magnetization and exchange bias in antiferromagnet (AFM)/ferromagnet (FM) heterostructures 1-10 is expected to be of use in several high-performance spintronic devices, including magnetic tunnel junctions and magnetoresistance sensors. An efficient method for electrical switching of the FM magnetization is to use the spin-orbit torque (SOT) generated from a heavy metal (such as W, Ta, Pt) layer in AFM/FM/heavy metal structures 4,5,[11][12][13][14] .The in-plane exchange field generated at the AFM/FM interface enables field-free switching of the perpendicular magnetization and, compared to spin-transfer torque (STT)-driven devices, SOTdriven systems can potentially offer decreased switching times and thus faster data writing 15 .However, manipulation of the exchange bias is usually achieved by field cooling, which requires an external magnetic field and high temperature, hindering its application in practical devices 1,16,17 .Alternatively, it has recently been demonstrated that the exchange bias field at the AFM/FM interface can be switched by the SOT generated in the Pt layer in a Pt/Co/IrMn structure, passing through the thin Co layer 6 . Strong SOTs can also be generated in certain AFM thin films (such as IrMn and PtMn) due to their giant spin Hall angle [18][19][20][21][22] , allowing simpler spintronic devices to be created [23][24][25] . For example, field-free switching of perpendicular magnetization has been achieved in PtMn/[Co/Ni]n structures where no heavy metal layer is required, with both the in-plane exchange bias and SOT originating from the AFM/FM system 23 . An advantage of using an AFM/FM/oxide stack is that it is easier, compared to AFM/FM/heavy metal structures, to integrate tunnelling magnetoresistance (for electrical reading of FM magnetization 26,27 ), SOT and exchange bias switching in a single device.In this Article, we repo...

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“…In thin films the number of pinned spins was observed to be in the range of 4-20 % [9]. More distant magnetic moments of AF follow the ordinary antiparallel ordering.…”

Section: Introductionmentioning

confidence: 95%

The influence of oxidation process on exchange bias in egg-shaped FeO/Fe3O4 core/shell nanoparticles

Leszczyński

Hadjipanayis

El-Gendy

et al. 2016

Journal of Magnetism and Magnetic Materials

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Micromagnetic Approach to Exchange Bias

Cited by 12 publications

References 27 publications

Design and Application of Magnetic Photocatalysts for Water Treatment. The Effect of Particle Charge on Surface Functionality

Design and Application of Magnetic Photocatalysts for Water Treatment. The Effect of Particle Charge on Surface Functionality

Exchange bias switching in an antiferromagnet/ferromagnet bilayer driven by spin–orbit torque

The influence of oxidation process on exchange bias in egg-shaped FeO/Fe3O4 core/shell nanoparticles

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