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Magnetic patterning: local manipulation of the intergranular exchange coupling via grain boundary engineering.

Huang KF, Liao JW, Hsieh CY, Wang LW, Huang YC, Wen WC, Chang MT, Lo SC, Yuan J, Lin HH, Lai CH - Sci Rep (2015)

Bottom Line: As demonstration, the grain boundary structure of Co/Pt multilayers is engineered by thermal treatment, where the stress state of the multilayers and thus the intergranular exchange coupling can be modified.With Ag passivation layers on top of the Co/Pt multilayers, we can hinder the stress relaxation and grain boundary modification.Combining the pre-patterned Ag passivation layer with thermal treatment, we can design spatial variations of the magnetic properties by tuning the intergranular exchange coupling, which diversifies the magnetic patterning process and extends its feasibility for varieties of new devices.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, 300, Taiwan.

ABSTRACT
Magnetic patterning, with designed spatial profile of the desired magnetic properties, has been a rising challenge for developing magnetic devices at nanoscale. Most existing methods rely on locally modifying magnetic anisotropy energy or saturation magnetization, and thus post stringent constraints on the adaptability in diverse applications. We propose an alternative route for magnetic patterning: by manipulating the local intergranular exchange coupling to tune lateral magnetic properties. As demonstration, the grain boundary structure of Co/Pt multilayers is engineered by thermal treatment, where the stress state of the multilayers and thus the intergranular exchange coupling can be modified. With Ag passivation layers on top of the Co/Pt multilayers, we can hinder the stress relaxation and grain boundary modification. Combining the pre-patterned Ag passivation layer with thermal treatment, we can design spatial variations of the magnetic properties by tuning the intergranular exchange coupling, which diversifies the magnetic patterning process and extends its feasibility for varieties of new devices.

No MeSH data available.


Demonstration on the proposed magnetic patterning method.(a) A flowchart of the proposed magnetic patterning process. (b) Hysteresis loops of the magnetic patterned Co/Pt MLs acquired from different regions by FMOKE. (c) AFM (upper row) and corresponding MFM images (lower row) of magnetic patterned Co/Pt MLs. The left (right) shows the partially saturated (ac-demagnetized) state with different width ratios of Ag-capped to uncapped stripes.
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f1: Demonstration on the proposed magnetic patterning method.(a) A flowchart of the proposed magnetic patterning process. (b) Hysteresis loops of the magnetic patterned Co/Pt MLs acquired from different regions by FMOKE. (c) AFM (upper row) and corresponding MFM images (lower row) of magnetic patterned Co/Pt MLs. The left (right) shows the partially saturated (ac-demagnetized) state with different width ratios of Ag-capped to uncapped stripes.

Mentions: The flowchart of the proposed method for magnetic pattering is shown in Fig. 1(a). First, 20 nm thick Ag lines with different line width are pre-patterned on Co/Pt MLs by e-beam lithography and lift-off. Before RTA, the whole sample shows uniform magnetic properties. The sample is then annealed by using RTA in vacuum (5 × 10−5 Torr) with duration of 20 seconds. Regions with or without Ag capping show different responses to RTA, leading to heterogeneous distributions of the magnetic properties in different spatial regions. After RTA, the remaining Ag patterns can be selectively etched away by ammonia-based etching solution (NH4OH:H2O2 = 1:1) without damages to the magnetic properties of Co/Pt MLs (see supplementary Figure 1), yielding a flat magnetic film with spatially manipulated magnetic properties.


Magnetic patterning: local manipulation of the intergranular exchange coupling via grain boundary engineering.

Huang KF, Liao JW, Hsieh CY, Wang LW, Huang YC, Wen WC, Chang MT, Lo SC, Yuan J, Lin HH, Lai CH - Sci Rep (2015)

Demonstration on the proposed magnetic patterning method.(a) A flowchart of the proposed magnetic patterning process. (b) Hysteresis loops of the magnetic patterned Co/Pt MLs acquired from different regions by FMOKE. (c) AFM (upper row) and corresponding MFM images (lower row) of magnetic patterned Co/Pt MLs. The left (right) shows the partially saturated (ac-demagnetized) state with different width ratios of Ag-capped to uncapped stripes.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4496669&req=5

f1: Demonstration on the proposed magnetic patterning method.(a) A flowchart of the proposed magnetic patterning process. (b) Hysteresis loops of the magnetic patterned Co/Pt MLs acquired from different regions by FMOKE. (c) AFM (upper row) and corresponding MFM images (lower row) of magnetic patterned Co/Pt MLs. The left (right) shows the partially saturated (ac-demagnetized) state with different width ratios of Ag-capped to uncapped stripes.
Mentions: The flowchart of the proposed method for magnetic pattering is shown in Fig. 1(a). First, 20 nm thick Ag lines with different line width are pre-patterned on Co/Pt MLs by e-beam lithography and lift-off. Before RTA, the whole sample shows uniform magnetic properties. The sample is then annealed by using RTA in vacuum (5 × 10−5 Torr) with duration of 20 seconds. Regions with or without Ag capping show different responses to RTA, leading to heterogeneous distributions of the magnetic properties in different spatial regions. After RTA, the remaining Ag patterns can be selectively etched away by ammonia-based etching solution (NH4OH:H2O2 = 1:1) without damages to the magnetic properties of Co/Pt MLs (see supplementary Figure 1), yielding a flat magnetic film with spatially manipulated magnetic properties.

Bottom Line: As demonstration, the grain boundary structure of Co/Pt multilayers is engineered by thermal treatment, where the stress state of the multilayers and thus the intergranular exchange coupling can be modified.With Ag passivation layers on top of the Co/Pt multilayers, we can hinder the stress relaxation and grain boundary modification.Combining the pre-patterned Ag passivation layer with thermal treatment, we can design spatial variations of the magnetic properties by tuning the intergranular exchange coupling, which diversifies the magnetic patterning process and extends its feasibility for varieties of new devices.

View Article: PubMed Central - PubMed

Affiliation: Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, 300, Taiwan.

ABSTRACT
Magnetic patterning, with designed spatial profile of the desired magnetic properties, has been a rising challenge for developing magnetic devices at nanoscale. Most existing methods rely on locally modifying magnetic anisotropy energy or saturation magnetization, and thus post stringent constraints on the adaptability in diverse applications. We propose an alternative route for magnetic patterning: by manipulating the local intergranular exchange coupling to tune lateral magnetic properties. As demonstration, the grain boundary structure of Co/Pt multilayers is engineered by thermal treatment, where the stress state of the multilayers and thus the intergranular exchange coupling can be modified. With Ag passivation layers on top of the Co/Pt multilayers, we can hinder the stress relaxation and grain boundary modification. Combining the pre-patterned Ag passivation layer with thermal treatment, we can design spatial variations of the magnetic properties by tuning the intergranular exchange coupling, which diversifies the magnetic patterning process and extends its feasibility for varieties of new devices.

No MeSH data available.