Magnetic structure and anisotropy of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mrow><mml:mo>[</mml:mo><mml:mrow><mml:mi>Co</mml:mi><mml:mo>/</mml:mo><mml:mi>Pd</mml:mi></mml:mrow><mml:mo>]</mml:mo></mml:mrow><mml:mn>5</mml:mn></mml:msub><mml:mo>/</mml:mo><mml:mi>NiFe</mml:mi></mml:mrow></mml:math>multilayers

Tryputen, Larysa; Guo, Feng; Liu, Frank; Nguyen, Tu N.; Mohseni, Seyed Majid; Chung, Sunjae; Fang, Yeyu; Åkerman, Johan; McMichael, Robert D.; Ross, Caroline A.

doi:10.1103/physrevb.91.014407

Cited by 26 publications

(20 citation statements)

References 27 publications

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“…While a fully perpendicular STNO, such as that assumed in the original prediction of droplets [40], would have the lowest nucleation current, it would on the other hand also not have any output signal, since the symmetry of the magnetodynamics would not generate a time-varying STNO resistance. Instead we argue that a fixed layer based on tilted anisotropy materials [51][52][53][54][55][56][57][58][59][60] would be ideal for droplet nucleation and operation. In Fig.…”

Section: Magnetic Droplet Nucleation Current Vs Fieldmentioning

confidence: 99%

Magnetic droplet solitons in orthogonal spin valves

Chung

Mohseni

Eklund

et al. 2015

Low Temperature Physics

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We review the recent experimental advancements in the realization and understanding of magnetic droplet solitons generated by spin transfer torque in orthogonal nanocontact based spin torque nanooscillators (STNOs) fabricated on extended spin valves and spin valve nanowires. The magnetic droplets are detected and studied using the STNO microwave signal and its resistance, the latter both quasistatically and time-resolved. The droplet nucleation current is found to have a minimum at intermediate magnetic field strengths and the nature of the nucleation changes gradually from a single sharp step well above this field, mode-hopping around the minimum, and continuous at low fields. The mode-hopping and continuous transitions are ascribed to droplet drift instability and re-nucleation at different time scales, which is corroborated by time-resolved measurements. We argue that the use of tilted anisotropy fixed layers could reduce the nucleation current further, move the nucleation current minimum to lower fields, and potentially remove the need for an applied magnetic field altogether. Finally, evidence of an edge mode droplet in a nanowire is presented. PACS: 75.30.Ds Spin waves;75.75.-c Magnetic properties of nanostructures.

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Section: Magnetic Droplet Nucleation Current Vs Fieldmentioning

confidence: 99%

Magnetic droplet solitons in orthogonal spin valves

Chung

Mohseni

Eklund

et al. 2015

Low Temperature Physics

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“…such as Scanning Probe Microscopy [17], Lorentz transmission electron microscopy [14][15], and magnetic-force microscopy [6,9], et al [13,[18][19][20], were used to the detection of magnetic bubbles in ultrathin films. The formation of magnetic bubble depends on some factors [9,26], such as the quality factor 2 2 / s u M K Q   (the ratio of the perpendicular magnetic anisotropy and magnetostatic energies). If Q>1, the stripe domains are formed in magnetic films.…”

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confidence: 99%

“…the soft NiFe and hard [Co/Pd]4 layers[25][26]: exchange constant VSM measurement. To ensure the labyrinth domain in Py layer, an effective non-zero perpendicular magnetic anisotropy K is taken…”

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confidence: 99%

Metastable magnetic bubble in [Co/Pd]₄/Py multilayers

Wei

Song

et al. 2018

J. Phys. D: Appl. Phys.

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Magnetic bubbles are topologically spin textures that offering the interesting physics and great promise for next-generation information storage technologies. The main obstacles so far are that magnetic bubbles are generated with no field stimuli in new material systems at room temperature. Here, we report the observation of individual magnetic bubbles and its high frequency measurement at room temperature in an exchange-coupled [Co/Pd]4/Py multilayers. We demonstrate that the emergence of magnetic bubbles at remanence can be tuned by the in-plane tilted magnetic field (roughly 3°) along the film plane at room temperature. High frequency results indicate that the presence of magnetic bubbles leads to broadening of the magnetic permeability spectrum lines (due to the non-uniformity of the magnetic moments). Our findings open the door to the bubble-based spintronics at room temperature in exchange-coupled magnetic multilayers.

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“…Ferromagnetic domains formed in the Co/Pd will dictate the formation of AFM domains in Cr 2 O 3 as well as the net averaged exchange bias field, H EB . Domain sizes in Co/Pd multilayers vary widely and are highly dependent on the thickness of the individual Co and Pd layers, the number of repeats, the seed layer, and the growth conditions . Magnetic force microscopy (MFM) scans (Figure b and Figure S3‐1, Supporting Information) of our exchange biased sample in a demagnetized state shows the presence of stripe domains, a pattern characteristic of perpendicular anisotropy Co/Pt and Co/Pd multilayers system, with a median domain width ≈350 nm.…”

Section: Resultsmentioning

confidence: 93%

Local Writing of Exchange Biased Domains in a Heterostructure of Co/Pd Pinned by Magnetoelectric Chromia

Singh

Echtenkamp

Street

et al. 2016

Adv Funct Materials

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wileyonlinelibrary.comto an understanding of EB. In reality, the formation of antiferromagnetic domains, either lateral [9] or through the depth of the film, [10] will reduce the EB field. In addition, atomic level roughness and defects at the interface can have a significant impact on the density of uncompensated surface spins, also reducing the net exchange bias.Here, we demonstrate laser written domains of EB in a heterostructure consisting of a 300 nm film of Cr 2 O 3 (0001) and perpendicular anisotropic Co/Pd multilayers. The spatial and temperature dependence of the EB will constrain the resolution of the domains that can be written. Careful measurements of the temperature dependence reveal a narrow distribution of blocking temperatures and spatially resolved measurements indicate that the spatial variations in EB are minimal. Both are facilitated by the robust roughness insensitive boundary magnetization [11,12] of Cr 2 O 3 , a well-known magnetoelectric (ME) AFM insulator with a bulk Néel temperature of 307 K. The boundary magnetization (BM) is present at the (0001) surface below the Néel temperature, enabled by the symmetry properties of magnetoelectric antiferromagnets [11][12][13] and is coupled to the AFM order parameter. Below the Néel temperature, two equivalent AFM domain configurations (and corresponding boundary magnetizations) [11,12] are possible. The roughness insensitive boundary magnetization fundamentally alters the EB mechanism-the statistical fluctuations seen in the Malozemoff model [14] and the influence of defects do not play a role. Note that in our sample, the very large exchange bias that would be expected in the presence of this robust boundary magnetization is dramatically reduced due to the presence of the 5 A Pd seed layer. We demonstrate local control of the EB using a focused laser beam and show that the ultimate size of these local regions may be manipulated by extrinsic controls, including the focusing optics, the power of the laser and the speed of writing. The process of domain writing involves the systematic control of sample temperature, the magnetization state of the FM layer, and the application of controlled localized heating provided by the focused laser beam. At a fundamental materials level, the unique boundary magnetization of Cr 2 O 3 provides excellent intrinsic control over the exchange bias. We will show that the narrow distribution of blocking temperatures facilitates the ability to write well-defined patterns of exchange bias. Technologically, our work demonstrates the possibility of using heat-assisted magnetic recording (HAMR) to write a state variable by altering the EB, rather than the coercivity, of magnetic memory cells. The increased stability of EB coupledThe writing of micrometerscaled exchange bias domains by local, laser heating of a thinfilm heterostructure consisting of a perpendicular aniso tropic ferromagnetic Co/Pd multilayer and a (0001) oriented film of the mag netoelectric antiferromagnet Cr 2 O 3 (chromia) is reported. Exchange coupling b...

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Magnetic structure and anisotropy of[Co/Pd]5/NiFemultilayers

Cited by 26 publications

References 27 publications

Magnetic droplet solitons in orthogonal spin valves

Magnetic droplet solitons in orthogonal spin valves

Metastable magnetic bubble in [Co/Pd]₄/Py multilayers

Local Writing of Exchange Biased Domains in a Heterostructure of Co/Pd Pinned by Magnetoelectric Chromia

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Magnetic structure and anisotropy of[Co/Pd]5/NiFemultilayers

Cited by 26 publications

References 27 publications

Magnetic droplet solitons in orthogonal spin valves

Magnetic droplet solitons in orthogonal spin valves

Metastable magnetic bubble in [Co/Pd]4/Py multilayers

Local Writing of Exchange Biased Domains in a Heterostructure of Co/Pd Pinned by Magnetoelectric Chromia

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Metastable magnetic bubble in [Co/Pd]₄/Py multilayers