The study of perpendicular magnetic anisotropy in CoFeB sandwiched by MgO and tantalum layers using polarized neutron reflectometry

Zhu, Tao; Yang, Yi; Yu, Richeng; Ambaye, Hailemariam; Lauter, Valeria; Xiao, John Q.

doi:10.1063/1.4718423

Cited by 49 publications

(26 citation statements)

References 27 publications

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“…It was experimentally found that Ta layer was very crucial for obtaining PMA [7,[10][11][12]. Some argued that Ta could diffuse into the interface of CoFeB/MgO to destroy the orbital hybridization, which is harmful for achieving PMA [7,10,12].…”

Section: Introductionmentioning

confidence: 97%

“…The system of CoFeB/MgO was one of the best materials for low magnetostriction and high MR. PMA has been achieved through adjusting the thickness and composition of CoFeB layer due to the proper orbital hybridization of Co-O or Fe-O [2,7,[10][11][12]. It was experimentally found that Ta layer was very crucial for obtaining PMA [7,[10][11][12].…”

Section: Introductionmentioning

confidence: 98%

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Interaction of Ta–O and perpendicular magnetic anisotropy of Ta/Pd (0–2.4 nm)/Co2FeAl0.5Si0.5/MgO/Ta structured films

Chen

Zhang

et al. 2015

Journal of Magnetism and Magnetic Materials

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 98%

Interaction of Ta–O and perpendicular magnetic anisotropy of Ta/Pd (0–2.4 nm)/Co2FeAl0.5Si0.5/MgO/Ta structured films

Chen

Zhang

et al. 2015

Journal of Magnetism and Magnetic Materials

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“…The two distinct switching fields suggest that the two CoFeB layers have different perpendicular magnetic anisotropy fields. The magnetizations characterized by polarized neutron reflectometry are 663 emu/cm 3 and 906 emu/cm 3 for top layer and bottom layer, respectively23. The bottom layer with the high magnetization has a small PMA and the small switching field is H 1 = 29 Oe, while the top layer with the low magnetization has a large PMA and the large switching field is H 2 = 84 Oe.…”

Section: Resultsmentioning

confidence: 99%

Ultrafast demagnetization enhancement in CoFeB/MgO/CoFeB magnetic tunneling junction driven by spin tunneling current

Zhu

Zhang

et al. 2013

Sci Rep

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The laser-induced ultrafast demagnetization of CoFeB/MgO/CoFeB magnetic tunneling junction is exploited by time-resolved magneto-optical Kerr effect (TRMOKE) for both the parallel state (P state) and the antiparallel state (AP state) of the magnetizations between two magnetic layers. It was observed that the demagnetization time is shorter and the magnitude of demagnetization is larger in the AP state than those in the P state. These behaviors are attributed to the ultrafast spin transfer between two CoFeB layers via the tunneling of hot electrons through the MgO barrier. Our observation indicates that ultrafast demagnetization can be engineered by the hot electrons tunneling current. It opens the door to manipulate the ultrafast spin current in magnetic tunneling junctions.

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“…[15][16][17][18] In this paper, we propose a new approach to manipulate the strength of PMA at films. [6][7][8][9][10][11]19,20] The Hall resistivity measurements were measured by using standard cross-structure four points in a physical property measurement system (PPMS, Quantum Design PPMS-14T) within the temperature range of 5 -300 K. The longitudinal resistivity was measured in the same sample from another channel of PPMS at same time. The magnetoresistance in all films at 5 T is smaller than 0.3%.…”

Section: Introductionmentioning

confidence: 99%

Tuning perpendicular magnetic anisotropy in the MgO/CoFeB/Ta thin films

Zhu

Zhang

2015

2015 IEEE Magnetics Conference (INTERMAG)

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By submonolayer insertion of Au, Pt, or Pd into Ta / CoFeB / MgO / Ta heterostructures we tune the perpendicular magnetic anisotropy and the coercive field of the ferromagnetic layer. We demonstrate that this has a major influence on the spin Hall switching current density and its dependence on the external magnetic field. Despite a rather small effective spin Hall angle of θ SH ≈ −0.07, we obtain switching current densities as low as 2 × 10 10 A/m 2 with a 2 ˚ A Au interlayer. We find that the Dzyaloshinskii-Moriya interaction parameter D is reduced with Au or Pd interlayers, and the perpendicular anisotropy field is reduced by an order of magnitude with the Pd interlayer. The dependence of the switching current density on the current pulse width is quantitatively explained with a domain wall nucleation and propagation model. Interface engineering is thus found to be a suitable route to tailor the current-induced magnetization switching properties of magnetic heterostructures. The ability of spin-orbit torques, and in particular of the spin Hall effect 1-3 (SHE), to generate spin currents that can be used to manipulate the magnetization of an ultrathin magnetic film has triggered very active research of the spintronics community on this novel field. The spin current generated through the SHE in a heavy metal film creates effective fields in an adjacent magnetic film which can be strong enough to excite magnetization dynamics and even magnetization switching. 4 The pivotal quantity of the SHE is the spin Hall angle θ SH = j s /j describing the ratio of the spin current j s and the orthogonal charge current j. Large values of the spin Hall angle were reported for the systems Ta / CoFeB (θ SH = −0.12), Pt / Co (θ SH = 0.07) and β-W / CoFeB (θ SH = −0.4). 5-9 In recent works the role of the interfaces of the ferro-magnetic film was studied. 10-13 The interfaces are decisive for the perpendicular magnetic anisotropy, 10 interlayers between the heavy metal and the ferromagnet can significantly alter the spin transmission and thereby lead to a change of the observed spin Hall angle, 11,12 and ferromagnetic layers decorated with ultrathin C layers were shown to have significantly modified perpendicular magnetic anisotropy (PMA) and effective spin Hall angle. In the present work we study the influence of submono-layer noble metal films inserted between a Ta film and an ultrathin CoFeB layer with PMA. We demonstrate that the PMA and the coercive fields depend sensitively on the choice of interlayer material and that the switching current density is greatly reduced with respect to the reference system without an interlayer. Most remarkably, we find that despite the spin Hall angle of our Ta film is comparatively small, small switching current densities are observed, which we ascribe to the very low PMA or the small coercive field of the ferromagnetic layer with a noble metal interlayer. Thin films of the type Si substrate / SiO x 50 nm / Ta 6 nm / NM 0.2 nm / CoFeB 0.7 nm / MgO 1.7 nm / Ta 1.5 nm (noble metal NM = Pt, Pd,...

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The study of perpendicular magnetic anisotropy in CoFeB sandwiched by MgO and tantalum layers using polarized neutron reflectometry

Cited by 49 publications

References 27 publications

Interaction of Ta–O and perpendicular magnetic anisotropy of Ta/Pd (0–2.4 nm)/Co2FeAl0.5Si0.5/MgO/Ta structured films

Interaction of Ta–O and perpendicular magnetic anisotropy of Ta/Pd (0–2.4 nm)/Co2FeAl0.5Si0.5/MgO/Ta structured films

Ultrafast demagnetization enhancement in CoFeB/MgO/CoFeB magnetic tunneling junction driven by spin tunneling current

Tuning perpendicular magnetic anisotropy in the MgO/CoFeB/Ta thin films

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