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Modification of perpendicular magnetic anisotropy and domain wall velocity in Pt/Co/Pt by voltage-induced strain.

Shepley PM, Rushforth AW, Wang M, Burnell G, Moore TA - Sci Rep (2015)

Bottom Line: K(eff), measured by the extraordinary Hall effect, is reduced by 10 kJ/m(3) by tensile strain out-of-plane ε(z) = 9 × 10(-4), independently of the film thickness, indicating a dominant volume contribution to the magnetostriction.The same strain reduces the coercive field by 2-4 Oe, and increases the domain wall velocity measured by wide-field Kerr microscopy by 30-100%, with larger changes observed for thicker Co layers.We consider how strain-induced changes in the perpendicular magnetic anisotropy can modify the coercive field and domain wall velocity.

View Article: PubMed Central - PubMed

Affiliation: School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, United Kingdom.

ABSTRACT
The perpendicular magnetic anisotropy K(eff), magnetization reversal, and field-driven domain wall velocity in the creep regime are modified in Pt/Co(0.85-1.0 nm)/Pt thin films by strain applied via piezoelectric transducers. K(eff), measured by the extraordinary Hall effect, is reduced by 10 kJ/m(3) by tensile strain out-of-plane ε(z) = 9 × 10(-4), independently of the film thickness, indicating a dominant volume contribution to the magnetostriction. The same strain reduces the coercive field by 2-4 Oe, and increases the domain wall velocity measured by wide-field Kerr microscopy by 30-100%, with larger changes observed for thicker Co layers. We consider how strain-induced changes in the perpendicular magnetic anisotropy can modify the coercive field and domain wall velocity.

No MeSH data available.


Related in: MedlinePlus

(a) Polar MOKE hysteresis loops of Pt/Co(t)/Pt with t = 0.85 nm (blue lines), 0.95 nm (green lines) and 1.0 nm (red lines). The solid lines represent the unstrained films and the dashed lines show the hysteresis loops under tensile out-of-plane strain induced by applying 150 V to the piezoelectric transducers. (b) The coercive fields of the hysteresis loops are plotted against Co thickness. The solid shapes are the unstrained films and the open shapes are the strained films. The error bars are smaller than the data points.
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f2: (a) Polar MOKE hysteresis loops of Pt/Co(t)/Pt with t = 0.85 nm (blue lines), 0.95 nm (green lines) and 1.0 nm (red lines). The solid lines represent the unstrained films and the dashed lines show the hysteresis loops under tensile out-of-plane strain induced by applying 150 V to the piezoelectric transducers. (b) The coercive fields of the hysteresis loops are plotted against Co thickness. The solid shapes are the unstrained films and the open shapes are the strained films. The error bars are smaller than the data points.

Mentions: Next we study the effects of strain on the magnetization reversal of Pt/Co/Pt. Hysteresis loops were measured using polar magneto-optical Kerr effect (MOKE). The sweep rate in the range of the coercive field was 2 Oe/s and five separate loops were averaged to obtain the data for each loop in Figure 2a. The polar MOKE hysteresis loops for 0.85, 0.95 and 1.0 nm Co all have the square shape typical of a perpendicular easy axis. The coercive field is largest for the 0.85 nm Co layer, which has the highest PMA, and decreases as the Co becomes thicker. For all three Co thicknesses the coercive field of the magnetic hysteresis loops is reduced by between 2 and 4 Oe under tensile strain (Figure 2b). As the PMA is modified, the energy barrier to magnetization reversal is lowered so that a smaller magnetic field is needed.


Modification of perpendicular magnetic anisotropy and domain wall velocity in Pt/Co/Pt by voltage-induced strain.

Shepley PM, Rushforth AW, Wang M, Burnell G, Moore TA - Sci Rep (2015)

(a) Polar MOKE hysteresis loops of Pt/Co(t)/Pt with t = 0.85 nm (blue lines), 0.95 nm (green lines) and 1.0 nm (red lines). The solid lines represent the unstrained films and the dashed lines show the hysteresis loops under tensile out-of-plane strain induced by applying 150 V to the piezoelectric transducers. (b) The coercive fields of the hysteresis loops are plotted against Co thickness. The solid shapes are the unstrained films and the open shapes are the strained films. The error bars are smaller than the data points.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4300497&req=5

f2: (a) Polar MOKE hysteresis loops of Pt/Co(t)/Pt with t = 0.85 nm (blue lines), 0.95 nm (green lines) and 1.0 nm (red lines). The solid lines represent the unstrained films and the dashed lines show the hysteresis loops under tensile out-of-plane strain induced by applying 150 V to the piezoelectric transducers. (b) The coercive fields of the hysteresis loops are plotted against Co thickness. The solid shapes are the unstrained films and the open shapes are the strained films. The error bars are smaller than the data points.
Mentions: Next we study the effects of strain on the magnetization reversal of Pt/Co/Pt. Hysteresis loops were measured using polar magneto-optical Kerr effect (MOKE). The sweep rate in the range of the coercive field was 2 Oe/s and five separate loops were averaged to obtain the data for each loop in Figure 2a. The polar MOKE hysteresis loops for 0.85, 0.95 and 1.0 nm Co all have the square shape typical of a perpendicular easy axis. The coercive field is largest for the 0.85 nm Co layer, which has the highest PMA, and decreases as the Co becomes thicker. For all three Co thicknesses the coercive field of the magnetic hysteresis loops is reduced by between 2 and 4 Oe under tensile strain (Figure 2b). As the PMA is modified, the energy barrier to magnetization reversal is lowered so that a smaller magnetic field is needed.

Bottom Line: K(eff), measured by the extraordinary Hall effect, is reduced by 10 kJ/m(3) by tensile strain out-of-plane ε(z) = 9 × 10(-4), independently of the film thickness, indicating a dominant volume contribution to the magnetostriction.The same strain reduces the coercive field by 2-4 Oe, and increases the domain wall velocity measured by wide-field Kerr microscopy by 30-100%, with larger changes observed for thicker Co layers.We consider how strain-induced changes in the perpendicular magnetic anisotropy can modify the coercive field and domain wall velocity.

View Article: PubMed Central - PubMed

Affiliation: School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, United Kingdom.

ABSTRACT
The perpendicular magnetic anisotropy K(eff), magnetization reversal, and field-driven domain wall velocity in the creep regime are modified in Pt/Co(0.85-1.0 nm)/Pt thin films by strain applied via piezoelectric transducers. K(eff), measured by the extraordinary Hall effect, is reduced by 10 kJ/m(3) by tensile strain out-of-plane ε(z) = 9 × 10(-4), independently of the film thickness, indicating a dominant volume contribution to the magnetostriction. The same strain reduces the coercive field by 2-4 Oe, and increases the domain wall velocity measured by wide-field Kerr microscopy by 30-100%, with larger changes observed for thicker Co layers. We consider how strain-induced changes in the perpendicular magnetic anisotropy can modify the coercive field and domain wall velocity.

No MeSH data available.


Related in: MedlinePlus