Coercivity enhancement above the Néel temperature of an antiferromagnet/ferromagnet bilayer

Leighton, Chris; Suhl, H.; Pechan, Michael J.; Compton, Robert; Nogués, J.; Schuller, Iván K.

doi:10.1063/1.1491277

Cited by 65 publications

(52 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…5 and 4, respectively. The difference in T B may be due to coercivity enhancement above T B as observed by Leighton et al [27] which is attributed to the spin fluctuations in the AFM layer inducing additional anisotropy in the FM layer.…”

Section: Fig 2 Mr Curves Of Co Wire Array For Various Temperaturesmentioning

confidence: 74%

Exchange bias effects in ferromagnetic wires

Husain

Adeyeye

Wang

et al. 2003

Journal of Magnetism and Magnetic Materials

View full text Add to dashboard Cite

We have investigated the exchange bias effect in micron-sized ferromagnetic wires made from Co and Ni 80 Fe 20 films. The wires were fabricated using optical lithography, metallization by sputtering and lift-off technique. Magnetotransport measurements were performed at temperatures ranging from 3 to 300 K. We observed marked changes in the magnetoresistance (MR) properties as the temperature is varied. At 300 K, the field at which the sharp peak occurs corresponding to the magnetization reversal of the Co wires is 167 Oe and is symmetrical about the origin. As the temperature was decreased to 3 K, we observed a shift in the peak positions of the MR characteristics for both the forward and reverse field sweeps corresponding to a loop shift of 582 Oe in the field axis. The asymmetric shift in the MR loops at low temperatures clearly indicates the exchange bias between ferromagnetic (Co) and antiferromagnetic parts (Co-oxide at the surfaces) from natural oxidation. Ni 80 Fe 20 wires of the same geometry showed similar effect with a low exchange bias field. The onset of exchange biasing effect is found to be 70 and 15 K for the Co and Ni 80 Fe 20 wires, respectively. A striking effect is the existence of exchange biasing effect from the sidewalls of the wires even when the wires were capped with Au film. r

show abstract

Section: Fig 2 Mr Curves Of Co Wire Array For Various Temperaturesmentioning

confidence: 74%

Exchange bias effects in ferromagnetic wires

Husain

Adeyeye

Wang

et al. 2003

Journal of Magnetism and Magnetic Materials

View full text Add to dashboard Cite

show abstract

“…Enhancement of the blocking temperature induced by EB was reported in Fe 0.6 Zn 0.4 F 2 (110)/Fe 14 nm/Ag 35 nm heterostructures [57], where it was attributed to the presence of Griffiths phase-like finite clusters. A coercivity enhancement was also reported in layered Fe/FeF 2 above T N , which was suggested to be due to the growth of spin fluctuations in the antiferromagnetic FeF 2 [58].…”

Section: Magnetic Characterizationmentioning

confidence: 83%

Probing core and shell contributions to exchange bias in Co/Co<inf>3</inf>O<inf>4</inf> nanoparticles of controlled size

De¹,

Iglesias

Majumdar

et al. 2017

2017 IEEE International Magnetics Conference (INTERMAG)

View full text Add to dashboard Cite

Coupling at the interface of core/shell magnetic nanoparticles is known to be responsible for exchange bias (EB) and the relative sizes of core and shell components are supposed to influence the associated phenomenology. In this work, we have prepared core/shell structured nanoparticles with a total average diameter around ∼27 nm and a wide range of shell thicknesses through the controlled oxidation of Co nanoparticles well dispersed in an amorphous silica host. Structural characterizations give compelling evidence of the formation of Co 3 O 4 crystallite phase at the shells surrounding the Co core. Field cooled hysteresis loops display nonmonotonous dependence of the exchange bias H E and coercive H C fields, that become maximum for a sample with an intermediate shell thickness, at which lattice strain is also maximum for both phases. The EB effects persist up to temperatures above the ordering temperature of the oxide shell. Results of our atomistic Monte Carlo simulations of particles with the same size and composition as in experiments are in agreement with the experimental observations and have allowed us to identify a change in the contribution of the interfacial surface spins to the magnetization reversal, giving rise to the observed maximum in H E and H C .

show abstract

“…17 ͑The different symmetries may also be a reason for piezomagnetism in these materials.͒ Alternative mechanisms that explain enhanced coercivity in exchange coupled bilayers and net magnetization in AF films attribute these phenomena to spin fluctuations on the AF surface. 18,19 Uncompensated spins in the antiferromagnet film bulk can affect exchange bias. For example, the combination of a net magnetization in a nominally antiferromagnetic material coupled with antiferromagnetic exchange coupling at the FM/AF interface can lead to a positive exchange bias ͑i.e., a shift of the hysteresis loop toward positive applied field, where positive means the applied and cooling fields are parallel͒.…”

Section: Introductionmentioning

confidence: 99%

Antiferromagnetic domain size and exchange bias

et al. 2008

Self Cite

View full text Add to dashboard Cite

Using neutron diffraction, we measured the sizes of antiferromagnetic domains in three ferromagnet/ antiferromagnet bilayer samples as a function of the magnitude and sign of exchange bias, temperature, and antiferromagnet composition. Neutron-scattering techniques were applied to thin films with masses less than 10 g. We found the antiferromagnetic domain size to be consistently small regardless of the exchange bias. For a Co/untwinned single crystalline antiferromagnet ͑AF͒-fluoride bilayer, the antiferromagnetic domain size is comparable to the crystallographic domain size of the AF. For one sample the highest temperature at which the exchange bias was nonzero ͑i.e., the blocking temperature͒ was suppressed by ϳ3 K compared to the Néel temperature of the antiferromagnet.

show abstract

Coercivity enhancement above the Néel temperature of an antiferromagnet/ferromagnet bilayer

Cited by 65 publications

References 33 publications

Exchange bias effects in ferromagnetic wires

Exchange bias effects in ferromagnetic wires

Probing core and shell contributions to exchange bias in Co/Co<inf>3</inf>O<inf>4</inf> nanoparticles of controlled size

Antiferromagnetic domain size and exchange bias

Contact Info

Product

Resources

About