Study of the dynamic magnetic properties of soft CoFeB films

Bilzer, C.; Devolder, T.; Kim, Joo-Von; Counil, G.; Chappert, C.; Cardoso, S.; Freitas, P. P.

doi:10.1063/1.2337165

Cited by 180 publications

(98 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…30. If we use an approximate value of from the literature 19,33 , the maximal change in damping is about 13% at I = 10 mA, corresponding to the current density of . In principle, higher driving current can be used to achieve further compensation over damping.…”

Section: Resultsmentioning

confidence: 99%

Control of propagating spin waves via spin transfer torque in a metallic bilayer waveguide

Birt

Pai

et al. 2014

Phys. Rev. B

View full text Add to dashboard Cite

We investigate the effect of a direct current on propagating spin waves in a CoFeB/Ta bilayer structure. Using the micro-Brillouin light scattering technique, we observe that the spin wave damping and amplitude may be attenuated or amplified depending on the direction of the current and the applied magnetic field. Our work suggests an effective approach for electrically controlling the propagation of spin waves in a magnetic waveguide and may be useful in a number of applications such as phase locked nano-oscillators and hybrid information processing devices.

show abstract

Section: Resultsmentioning

confidence: 99%

Control of propagating spin waves via spin transfer torque in a metallic bilayer waveguide

Birt

Pai

et al. 2014

Phys. Rev. B

View full text Add to dashboard Cite

show abstract

“…Common MTJ nanopillars differ qualitatively from the pseudo-spin-valves in three fundamental points: Firstly, with a free layer and a synthetic antiferromagnet (SAF) they consist of three magnetic layers; secondly, with 2 − 4 nm the layer thicknesses are now smaller than the exchange length, 14 such that, for sufficiently small lateral dimensions, the spin dynamics in each layer is dominated by the exchange interaction; thirdly, the interlayer interaction of the three layers is highly asymmetric: the two SAF layers are strongly coupled by interlayer exchange and -more weakly -mutual dipolar coupling, one of them (the pinned layer) being additionally subject to the strong exchange bias field; the free layer interacts with the SAF via the comparatively weak mutual dipolar coupling only. Consequently, the eigenexcitations of an MTJ nanopillar are expected to be much more complex than those of the pseudo-spin-valves.…”

Section: Introductionmentioning

confidence: 99%

Quantized spin-wave modes in magnetic tunnel junction nanopillars

et al. 2010

Self Cite

View full text Add to dashboard Cite

We present an experimental and theoretical study of the magnetic field dependence of the mode frequency of thermally excited spin waves in rectangular shaped nanopillars of lateral sizes 60 × 100, 75 × 150, and 105 × 190 nm 2 , patterned from MgO-based magnetic tunnel junctions. The spin wave frequencies were measured using spectrally resolved electrical noise measurements. In all spectra, several independent quantized spin wave modes have been observed and could be identified as eigenexcitations of the free layer and of the synthetic antiferromagnet of the junction. Using a theoretical approach based on the diagonalization of the dynamical matrix of a system of three coupled, spatially confined magnetic layers, we have modeled the spectra for the smallest pillar and have extracted its material parameters. The magnetization and exchange stiffness constant of the CoFeB free layer are thereby found to be substantially reduced compared to the corresponding thin film values. Moreover, we could infer that the pinning of the magnetization at the lateral boundaries must be weak. Finally, the interlayer dipolar coupling between the free layer and the synthetic antiferromagnet causes mode anticrossings with gap openings up to 2 GHz. At low fields and in the larger pillars, there is clear evidence for strong non-uniformities of the layer magnetizations. In particular, at zero field the lowest mode is not the fundamental mode, but a mode most likely localized near the layer edges.

show abstract

“…For example, recently, we theoretically reported on that the switching current density of the STT-MRAM is very sensitive to on the exchange stiffness constant of the free layer [5]. However, only a few experimental measurements have been reported for the exchange stiffness constant of CoFeB [6][7] [8], despite the exchange stiffness constant is a fundamental physical quantity and related with the number of nearest neighbor magnetic atoms and Curie temperature of materials [9], and it is important in the domain wall motion devices because it will determine the domain wall width and energy [10]. In the CoFeB/MgO/CoFeB multilayer stacks, it is well-known that careful annealing process is require in order to obtain huge TMR, because the formation of crystalline phase of CoFeB.…”

Section: Introductionmentioning

confidence: 99%