Effect of free layer thickness and shape anisotropy on the transfer curves of MgO magnetic tunnel junctions

Wiśniowski, P.; Almeida, José; Barradas, N.P.; Freitas, P. P.

doi:10.1063/1.2838626

Cited by 71 publications

(46 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Indeed, the sole criterion of maximal TMR would argue 11,15 for a large t 1 , leading to the loss of perpendicular magnetization at remanence when the demagnetizing energy µ 0 M 2 S /2 overcomes the interface anisotropy energy K S /t 1 . This can be relaxed and one can use thicker spin polarizing layer if one complements its interface anisotropy by a ferromagnetic interlayer exchange coupling J/t 1 with the high anisotropy layer.…”

Section: Introductionmentioning

confidence: 99%

Ferromagnetic resonance of exchange-coupled perpendicularly magnetized bilayers

Devolder

2016

Journal of Applied Physics

View full text Add to dashboard Cite

Strong ferromagnetic interlayer exchange couplings J in perpendicularly magnetized systems are becoming increasingly desirable for applications. We study whether ferromagnetic interlayer exchange couplings can be measured by a combination of broadband ferromagnetic resonance methods and magnetometry hysteresis loops. For this we model the switching and the eigenexcitations in bilayer systems comprising a soft layer coupled to a thicker harder layer that possesses higher perpendicular magnetic anisotropy. For large J > 0 the switching fields are essentially independent of J but the frequency of the optical eigenmode of the bilayer and the linewidth of the acoustical and optical eigenmode are directly sensitive to the coupling. We derive a corpus of compact analytical expressions to analyze these frequencies, their linewidth and discuss the meaning thereof. We illustrate this corpus on a system mimicking the fixed layers of a magnetic tunnel junction meant for spin torque applications.

show abstract

Section: Introductionmentioning

confidence: 99%

Ferromagnetic resonance of exchange-coupled perpendicularly magnetized bilayers

Devolder

2016

Journal of Applied Physics

View full text Add to dashboard Cite

show abstract

“…[8][9][10] Recently, several groups proposed that a discontinuous ferromagnetic free layer can induce a linear response in MgO single barrier (SB-) or double barrier (DB-) MTJs. [11][12][13][14] When the free layer thickness is below a critical value, it breaks up into nanoislands on the MgO surface, which are superparamagnetic. [11][12][13][14][15] Realizing a linear response in DBMTJs, which have better bias dependence of TMR compared to SB-MTJs, [16][17][18] is advantageous for sensor applications.…”

mentioning

confidence: 99%

Field sensing in MgO double barrier magnetic tunnel junctions with a superparamagnetic Co50Fe50 free layer

Feng

Liu

et al. 2012

Journal of Applied Physics

View full text Add to dashboard Cite

Linear response and low frequency noise have been investigated in MgO double barrier magnetic tunnel junctions with a superparamagnetic Co 50 Fe 50 free layer. Linear and hysteresis-free switching was observed for the Co 50 Fe 50 thickness t 1 nm. A tunneling magnetoresistance ratio of up to 108% and large magnetic field sensitivity value of 61%/mT were obtained at room temperature when t ¼ 1.0 nm. The angular dependence of magnetoresistance suggests that weak coupling between superparamagnetic islands in a 1.0 nm free layer permits continuous rotation of magnetization, whereas the islands in a 0.8 nm layer switch rather independently. The frequency dependence of noise power spectrum density and field dependence of Hooge parameter (a) also behave differently for junctions with 0.8 and 1.0 nm free layers. The noise sensitivity of 1.0 nm free layer junctions is independent of bias, and it is estimated to reach 400 pT/Hz 0.5 at 500 kHz. V C 2012 American Institute of Physics. [http://dx

show abstract

“…In order to increase spatial resolution of the device, the MTJ with nanometer-scale size was fabricated. Taking advantage of perpendicular interface magnetic anisotropy, we tuned the thicknesses of both layers to achieve orthogonal magnetization alignment, i.e., perpendicular magnetization for the sensing and in-plane magnetization for the reference layer [5]. The MgO tunnel barrier was thick enough to hamper any spin-transfer-torque related eects [6].…”

mentioning

confidence: 99%

Magnetic Field Sensor Based on Magnetic Tunnel Junction with Voltage-Tunable Magnetic Anisotropy

et al. 2015

Self Cite

View full text Add to dashboard Cite

We present a submicron magnetic eld sensor with voltage-tunable magnetic eld sensitivity. The device, based on magnetic tunnel junction, exhibits high tunnelling magnetoresistance ratio of up to 90 %. Perpendicular magnetic anisotropy of thin ferromagnetic sensing layer in combination with an in-plane magnetized reference layer is used to obtain linear change in the sensor resistance in response to the in-plane magnetic eld. The perpendicular anisotropy is further controlled by the bias voltage and, thus, the sensitivity of the sensor is changed. In addition, we evaluate the sensor selectivity for the magnetic eld direction and present an inuence of the temperature on the anisotropy.

show abstract

Effect of free layer thickness and shape anisotropy on the transfer curves of MgO magnetic tunnel junctions

Cited by 71 publications

References 9 publications

Ferromagnetic resonance of exchange-coupled perpendicularly magnetized bilayers

Ferromagnetic resonance of exchange-coupled perpendicularly magnetized bilayers

Field sensing in MgO double barrier magnetic tunnel junctions with a superparamagnetic Co50Fe50 free layer

Magnetic Field Sensor Based on Magnetic Tunnel Junction with Voltage-Tunable Magnetic Anisotropy

Contact Info

Product

Resources

About