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Efficient Synchronization of Dipolarly Coupled Vortex-Based Spin Transfer Nano-Oscillators.

Locatelli N, Hamadeh A, Abreu Araujo F, Belanovsky AD, Skirdkov PN, Lebrun R, Naletov VV, Zvezdin KA, Muñoz M, Grollier J, Klein O, Cros V, de Loubens G - Sci Rep (2015)

Bottom Line: This makes them interesting model systems to study the effects of synchronization and brings some opportunities to improve their microwave characteristics in view of their applications in information and communication technologies and/or to design innovative computing architectures.We experimentally study a pair of vortex-based spin transfer nano-oscillators, in which mutual synchronization can be achieved despite a significant frequency mismatch between oscillators.Importantly, the coupling efficiency is controlled by the magnetic configuration of the vortices, as confirmed by an analytical model and micromagnetic simulations highlighting the physics at play in the synchronization process.

View Article: PubMed Central - PubMed

Affiliation: Unité Mixte de Physique CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, F91767 Palaiseau, France.

ABSTRACT
Due to their nonlinear properties, spin transfer nano-oscillators can easily adapt their frequency to external stimuli. This makes them interesting model systems to study the effects of synchronization and brings some opportunities to improve their microwave characteristics in view of their applications in information and communication technologies and/or to design innovative computing architectures. So far, mutual synchronization of spin transfer nano-oscillators through propagating spinwaves and exchange coupling in a common magnetic layer has been demonstrated. Here we show that the dipolar interaction is also an efficient mechanism to synchronize neighbouring oscillators. We experimentally study a pair of vortex-based spin transfer nano-oscillators, in which mutual synchronization can be achieved despite a significant frequency mismatch between oscillators. Importantly, the coupling efficiency is controlled by the magnetic configuration of the vortices, as confirmed by an analytical model and micromagnetic simulations highlighting the physics at play in the synchronization process.

No MeSH data available.


Scheme of our coupled STNOs system.Two spin valve nanopillars with 2R = 200 nm diameter separated by a distance L = 100 nm. Each pillar contains a NiFe(4 nm)/Cu(10 nm)/NiFe(15 nm) spin valve (NiFe = Ni81Fe19) and a vortex is present in each 15 nm NiFe layers. The current is injected in parallel into the two pillars.
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f1: Scheme of our coupled STNOs system.Two spin valve nanopillars with 2R = 200 nm diameter separated by a distance L = 100 nm. Each pillar contains a NiFe(4 nm)/Cu(10 nm)/NiFe(15 nm) spin valve (NiFe = Ni81Fe19) and a vortex is present in each 15 nm NiFe layers. The current is injected in parallel into the two pillars.

Mentions: Our system is composed of two 2R = 200 nm diameter spin valve nanopillars separated by L = 100 nm. These STNOs are patterned by e-beam lithography and ion etching from a magnetic trilayer deposited by sputtering: NiFe(15 nm)/Cu(8 nm)/NiFe(4 nm) (see Fig. 1). From our previous studies on a single STNO made from the same trilayer stack, we observed that the magnetic configuration in the thicker NiFe layer is a magnetic vortex at remanence. Depending on the applied dc current, the configuration in the thin NiFe layer can be either a quasi-uniform magnetization or a second magnetic vortex333435. In both cases, the resulting spin transfer forces on the thick layer vortex can lead to the sustained excitation of the vortex core gyration if the current sign is appropriately chosen. In the case of two vortices, an important outcome was to demonstrate that highly coherent gyrotropic oscillations of the coupled vortices can be achieved when their core polarities are in opposite directions33343536. Further description of the sample can be found in the methods section.


Efficient Synchronization of Dipolarly Coupled Vortex-Based Spin Transfer Nano-Oscillators.

Locatelli N, Hamadeh A, Abreu Araujo F, Belanovsky AD, Skirdkov PN, Lebrun R, Naletov VV, Zvezdin KA, Muñoz M, Grollier J, Klein O, Cros V, de Loubens G - Sci Rep (2015)

Scheme of our coupled STNOs system.Two spin valve nanopillars with 2R = 200 nm diameter separated by a distance L = 100 nm. Each pillar contains a NiFe(4 nm)/Cu(10 nm)/NiFe(15 nm) spin valve (NiFe = Ni81Fe19) and a vortex is present in each 15 nm NiFe layers. The current is injected in parallel into the two pillars.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4660301&req=5

f1: Scheme of our coupled STNOs system.Two spin valve nanopillars with 2R = 200 nm diameter separated by a distance L = 100 nm. Each pillar contains a NiFe(4 nm)/Cu(10 nm)/NiFe(15 nm) spin valve (NiFe = Ni81Fe19) and a vortex is present in each 15 nm NiFe layers. The current is injected in parallel into the two pillars.
Mentions: Our system is composed of two 2R = 200 nm diameter spin valve nanopillars separated by L = 100 nm. These STNOs are patterned by e-beam lithography and ion etching from a magnetic trilayer deposited by sputtering: NiFe(15 nm)/Cu(8 nm)/NiFe(4 nm) (see Fig. 1). From our previous studies on a single STNO made from the same trilayer stack, we observed that the magnetic configuration in the thicker NiFe layer is a magnetic vortex at remanence. Depending on the applied dc current, the configuration in the thin NiFe layer can be either a quasi-uniform magnetization or a second magnetic vortex333435. In both cases, the resulting spin transfer forces on the thick layer vortex can lead to the sustained excitation of the vortex core gyration if the current sign is appropriately chosen. In the case of two vortices, an important outcome was to demonstrate that highly coherent gyrotropic oscillations of the coupled vortices can be achieved when their core polarities are in opposite directions33343536. Further description of the sample can be found in the methods section.

Bottom Line: This makes them interesting model systems to study the effects of synchronization and brings some opportunities to improve their microwave characteristics in view of their applications in information and communication technologies and/or to design innovative computing architectures.We experimentally study a pair of vortex-based spin transfer nano-oscillators, in which mutual synchronization can be achieved despite a significant frequency mismatch between oscillators.Importantly, the coupling efficiency is controlled by the magnetic configuration of the vortices, as confirmed by an analytical model and micromagnetic simulations highlighting the physics at play in the synchronization process.

View Article: PubMed Central - PubMed

Affiliation: Unité Mixte de Physique CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, F91767 Palaiseau, France.

ABSTRACT
Due to their nonlinear properties, spin transfer nano-oscillators can easily adapt their frequency to external stimuli. This makes them interesting model systems to study the effects of synchronization and brings some opportunities to improve their microwave characteristics in view of their applications in information and communication technologies and/or to design innovative computing architectures. So far, mutual synchronization of spin transfer nano-oscillators through propagating spinwaves and exchange coupling in a common magnetic layer has been demonstrated. Here we show that the dipolar interaction is also an efficient mechanism to synchronize neighbouring oscillators. We experimentally study a pair of vortex-based spin transfer nano-oscillators, in which mutual synchronization can be achieved despite a significant frequency mismatch between oscillators. Importantly, the coupling efficiency is controlled by the magnetic configuration of the vortices, as confirmed by an analytical model and micromagnetic simulations highlighting the physics at play in the synchronization process.

No MeSH data available.