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Current-induced magnetic domain wall motion below intrinsic threshold triggered by Walker breakdown
1Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan.
Nature Nanotechnology
|September 11, 2012
Summary
Researchers reduced the current density needed for magnetic domain wall motion by 40% using an external magnetic field. This finding could lead to more efficient non-volatile memory and logic devices.
Area of Science:
- Spintronics
- Condensed Matter Physics
- Materials Science
Background:
- Electric current can control magnetic domain walls for non-volatile memory.
- Reducing the threshold current density is crucial for practical applications.
- Intrinsic pinning in Co/Ni nanowires establishes a baseline current threshold, J(th)(0).
Purpose of the Study:
- Investigate methods to reduce the current density required for magnetic domain wall motion below J(th)(0).
- Explore the effect of an external magnetic field on domain wall dynamics.
- Determine if domain wall motion can be achieved at significantly lower current densities.
Main Methods:
- Utilized perpendicularly magnetized Co/Ni nanowires.
- Applied external magnetic fields of varying strengths.
- Measured domain wall motion induced by electric currents below J(th)(0).
- Analyzed domain wall velocity as a function of applied fields and currents.
Main Results:
- Domain wall motion was induced at current densities 40% below J(th)(0) with an optimal magnetic field.
- Domain wall velocity was observed as the vector sum of current- and field-induced components.
- Domain walls were driven against a 2,000 Oe magnetic field at currents below J(th)(0).
- This phenomenon was linked to Walker breakdown.
Conclusions:
- External magnetic fields can significantly reduce the required current density for domain wall motion.
- The additive velocity effect offers a novel method for determining spin polarization and Gilbert damping.
- This approach presents a pathway towards more energy-efficient spintronic devices.
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