Intrinsic Distribution of Magnetic Anisotropy in Thin Films Probed by Patterned Nanostructures

Thomson, Thomas; Hu, G.; Terris, B. D.

doi:10.1103/physrevlett.96.257204

Cited by 305 publications

(225 citation statements)

References 25 publications

Supporting

Mentioning

209

Contrasting

Order By: Relevance

“…This discrepancy with the Stoner-Wohlfarth theory mostly originates from non uniform reversal modes that are initiated in low anisotropy regions like misorientated grains ͑and thermal activation͒. 5 Besides, as far as SFD is concerned, chemical interfaces represent the leading anisotropy term, however, the layering has very little irregularities or defects, so it is only a second order contribution to the SFD. In contrast the crystalline orientation of the grains is a second order anisotropy term, while misaligned grains and corresponding variations in anisotropy generate the dominating term to the SFD.…”

Section: -mentioning

confidence: 99%

“…3,4 The SFD has multiple origins but intrinsic growth defects leading to anisotropy distribution has been shown to be a dominant one. [5][6][7][8] These defects include misorientated grains, grain boundaries, distribution of easy axis angle, variations in lattice stress, and variations in thicknesses or interface roughness in multilayers. Two recent investigations 7,8 indicate that misorientated crystalline grains are the major microstructural origin of SFD in ͑111͒ textured ͓Co/Pd͔ multilayers.…”

mentioning

confidence: 99%

“…3,5 These are polycrystalline systems with a highly ͑111͒ textured microstructure induced by the Ta/Pd seed layers. 9 The quality of the multilayering, in full films as well as in nanostructure arrays, has been shown in Ref.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Influence of ion irradiation on switching field and switching field distribution in arrays of Co/Pd-based bit pattern media

Hauet¹,

Hellwig

Park³

et al. 2011

Applied Physics Letters

Self Cite

View full text Add to dashboard Cite

International audienceWe have used ion irradiation to tune switching field and switching field distribution ͑SFD͒ in polycrystalline Co/Pd multilayer-based bit pattern media. Light He + ion irradiation strongly decreases perpendicular magnetic anisotropy amplitude due to Co/Pd interface intermixing, while the granular structure, i.e., the crystalline anisotropy, remains unchanged. In dot arrays, the anisotropy reduction leads to a decrease in coercivity ͑H C ͒ but also to a strong broadening of the normalized SFD/ H C ͑in percentage͒, since the relative impact of misaligned grains is enhanced. Our experiment thus confirms the major role of misorientated grains in SFD of nanodevice arrays. Today a major research effort in magnetism is targeted toward achieving ultrahigh density data storage with nano-scale magnets. Spin-transfer magnetic random access memory ͑spin-RAM͒ and bit patterned media ͑BPM͒ technologies are currently part of the most promising media. The implementation of both of these technologies relies on achieving in-detail physical understanding and control of the magnetization reversal mechanism in each nanoscopic individual bit to ensure reproducibility of the bit properties in order to avoid write errors. Perpendicular magnetic anisotropy ͑PMA͒ materials, such as polycrystalline Co/Pd, Co/Pt, and Co/Ni multilayers, are believed to be promising materials for both spin-RAM and BPM applications. 1–4 Indeed, they have a well defined high amplitude uniaxial anisotropy that provides good thermal stability while offering low critical current in spin-transfer devices 2 and tunable switching fields in BPM.

show abstract

Section: -mentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Influence of ion irradiation on switching field and switching field distribution in arrays of Co/Pd-based bit pattern media

Hauet¹,

Hellwig

Park³

et al. 2011

Applied Physics Letters

Self Cite

View full text Add to dashboard Cite

show abstract

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] The magnetization reversal process in these systems usually involves the formation of vertically correlated stripe domains, through the entire multilayer film stack resulting from a competition between ferromagnetic (FM) exchange, anisotropy and dipolar energies. 1 The energy balance can be further tailored through the addition of Ru spacer layers with appropriate thicknesses, which establishes antiferromagnetic (AF) interlayer exchange coupling.…”

Section: Introductionmentioning

confidence: 99%

Temperature-dependent magnetization reversal in(Co∕Pt)∕Rumultilayers

et al. 2008

View full text Add to dashboard Cite

TitleTemperature-dependent magnetization reversal in (Co/Pt)/Ru multilayers AbstractAntiferromagnetically coupled (Co/Pt)/Ru multilayers with perpendicular anisotropy have been shown to exhibit both vertically and laterally correlated magnetization reversal modes.In this work the magnetization reversal of a multilayer film whose layer thicknesses have been tuned to be at the phase boundary between the two reversal modes has been investigated as a function of temperature using the first-order reversal curve (FORC) method. At high temperatures reversal via vertically correlated stripe domains throughout the film thickness is observed, similar to that in Co/Pt films without the Ru spacers. At low temperatures antiferromagnetic (AF) interlayer exchange coupling dominates, and laterally correlated reversal is observed with an AF coupled remanent state. Under magnetic field cycling, dipolar fields can transform the sample back into a vertically correlated domain state, thus leading to an exotic behavior with FORC's existing outside the major hysteresis loop. Calculations show that the laterally correlated reversal mode is indeed slightly more stable, and the crossover to vertically correlated reversal can be induced by temperature as well as magnetic field.

show abstract

“…In fitting our data to this model we obtain a dimensionless energy barrier of ξ = 450, which is within 25% of that expected based on the volume, magnetization and anisotropy of the nanomagnet (ξ = M s H k V /(2kT ) = 360). Our previous results, as well as those of many other groups, have found energy barriers to reversal for long field [20][21][22][23] and long current pulses (> 100 ns) 9,10 to be only a small fraction of that expected for a macrospin, suggesting the reversal proceeds by subvolume nucleation 24,25 . For similar samples, we found that the energy barrier to reversal under long current pulses to be ≃ 60 k B T 9 , 1/6 the macrospin value.…”

Section: A→bmentioning

confidence: 94%

Time-resolved magnetic relaxation of a nanomagnet on subnanosecond time scales

Liu

Bedau

Sun³

et al. 2012

Phys. Rev. B

View full text Add to dashboard Cite

We present a two-current-pulse temporal correlation experiment to study the intrinsic subnanosecond nonequilibrium magnetic dynamics of a nanomagnet during and following a pulse excitation. This method is applied to a model spin-transfer system, a spin valve nanopillar with perpendicular magnetic anisotropy. Two-pulses separated by a short delay (< 500 ps) are shown to lead to the same switching probability as a single pulse with a duration that depends on the delay. This demonstrates a remarkable symmetry between magnetic excitation and relaxation and provides a direct measurement of the magnetic relaxation time. The results are consistent with a simple finite temperature Fokker-Planck macrospin model of the dynamics, suggesting more coherent magnetization dynamics in this short time nonequilibrium limit than near equilibrium.

show abstract

Intrinsic Distribution of Magnetic Anisotropy in Thin Films Probed by Patterned Nanostructures

Cited by 305 publications

References 25 publications

Influence of ion irradiation on switching field and switching field distribution in arrays of Co/Pd-based bit pattern media

Influence of ion irradiation on switching field and switching field distribution in arrays of Co/Pd-based bit pattern media

Temperature-dependent magnetization reversal in(Co∕Pt)∕Rumultilayers

Time-resolved magnetic relaxation of a nanomagnet on subnanosecond time scales

Contact Info

Product

Resources

About