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Nanolab highlight archive

nonlocal waveguide “ Excitation of coherent propagating spin waves by pure spin currents ” Nature Communications, 2016. In collaboration with the group of Sergej Demokritov at U.Muenster, we demonstrate a novel nanostructure based on the concepts of nonlocal spin injection and dipolar waveguides. Nonlocal spin injection is an approach to generating pure spin currents not accompanied by electrical currents, which is very useful for spintronic devices utilizing insulating materials. Dipolar waveguides developed by us in the last year enable efficient guiding of spin waves in profiled continuous magnetic films. In this paper, we demonstrated current-induced excitation of coherent spin waves directionally propagating in a dipolar waveguide. This advancement can enable the development of electronically operated magnonic nano-circuits that can store, transmit and process information, all on the same chip.

nonlocal “ Spin-current nano-oscillator based on nonlocal spin injection ” Scientific Reports (2015) In collaboration with the group of Sergej Demokritov at U.Muenster, we demonstrate the possibility to induce local oscillations in a magnetic film, by using a pure spin current injected in this film through a nonlocal point contact. Pure spin currents are flows of spin that are not directly tied to the electrical current. Pure spin currents do not require a concurrent path for the electrical current, provide unprecedented opportunities for the development of new, previously impossible, architectures of active spintronic devices. Using pure spin currents can also make spintronic devices more efficient, and minimize the effects of Joule heating and electromigration.

skyrmion “ Dynamical skyrmion state in spin-current nano-oscillator with perpendicular magnetic anisotropy” PRL,114, 137201 (2015) We use magnetoelectronic measurements and micromagnetic simulations to demonstrate the possibility to generate a topologically nontrivial nanoscale magnetic texture, by local injection of spin current into a thin magnetic film with perpendicular anisotropy. Such textures provide a fascinating model system for the elementary particles studied in high energy physics. They are also among the smallest known magnetic objects, and can provide a medium for the implementation of new magnetic storage and information processing devices. Previously, skyrmions have been experimentally studied only in bulk noncentrosymmetric crystals. Our research shows a pathway for their controllable generation and studies in thin-film nanostructures.

STNO waveguide “ Nanomagnonic devices based on the spin transfer torque ”, Nature Nanotech. (2014), also featured in this Journal's News and Views . In collaboration with the group of Sergej Demokritov at U. Muenster, we have proposed and demonstrated a nanoscale magnetic device that consists of a spin-torque nanocontact fabricated into a magnetic medium with a profiled thickness. In developing this device, we have introduced the concept of a dipolar field-induced dipolar field-induced magnetic nanowaveguides - magnetic strips with elevated profile whose dipolar fields can confine the propagating spin waves over a frequency range controlled by the geometry of the waveguide.\ This new concept provides a path for the development of magnonic structures that can serve as integrated spin wave-based filters and logic elements. Good spectral matching between the spin waves emitted by the spin-torque nanocontacts with the appropriately profiled waveguides results in efficient emission and directional propagation of spin waves, providing the first building block for the spin torque-driven nanomagnonics.

SHNO “ Spectral characteristics of microwave emission by a spin Hall nano-oscilaltor ”, PRL (2013), also featured in the Physics Viewpoint We have created a nanooscillator utilizing the spin Hall effect to induce microwave-frequency oscillations of a nanoscale magnet, and anisotropic magnetoresistance effect to convert these oscillations into electronic microwave signals. The simple planar structure of the device is amenable to a variety of modifications, providing a path for the studies of electron spin physics in nanoscale systems and development of novel active microwave spintronic nanodevices. Such nanoscale devices can be utilized in microwave communication technologies, as sensitive detectors of dc and microwave fields, and as local signal sources in magnonic devices.

field-effect diode “ Field-effect diode based on electron-induced Mott transition in NdNiO3 APL (2012). In collaboration with the group of Jaques Chakhalian at U. Arkansas and John Freeland at ANL, we have a field-efect device with diode-like electronic characteristics achieved due to the electric field-controlled metal-insulator Mott transition in a complex oxide NdNiO2. Because the metal-insulator transition is of the first order, the electrical characteristics of the device are hysteretic with respect to both the thermal and electrical history of the devices, providing an additional memristive functionality.

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