Generation of charge current from magnetization oscillation via the inverse of voltage-controlled magnetic anisotropy effect.

It is well known that oscillating magnetization induces charge current in a circuit via Faraday's law of electromagnetic induction. New physical phenomena by which magnetization dynamics can produce charge current have gained considerable interest recently. For example, moving magnetization textures, such as domain walls, generates charge current through the spin-motive force.

Abrupt p-n junction using ionic gating at zero-bias in bilayer graphene.

Graphene is a promising candidate for optoelectronic applications. In this report, a double gated bilayer graphene FET has been made using a combination of electrostatic and electrolytic gating in order to form an abrupt p-n junction. The presence of two Dirac peaks in the gating curve of the fabricated device confirms the formation of a p-n junction.

Gyrator Based on Magneto-elastic Coupling at a Ferromagnetic/Piezoelectric Interface.

A gyrator is a non-reciprocal two port device with 180° phase shift in the transmissions between two ports. Though electromagnetic realizations of gyrators have been well studied, devices based on other forms of interaction are relatively unexplored. Here we demonstrate a device in which signal is transmitted via magneto-elastic coupling, can function as a gyrator.

Coherent microwave generation by spintronic feedback oscillator.

The transfer of spin angular momentum to a nanomagnet from a spin polarized current provides an efficient means of controlling the magnetization direction in nanomagnets. A unique consequence of this spin torque is that the spontaneous oscillations of the magnetization can be induced by applying a combination of a dc bias current and a magnetic field. Here we experimentally demonstrate a different effect, which can drive a nanomagnet into spontaneous oscillations without any need of spin torque.

Proposal for a Domain Wall Nano-Oscillator driven by Non-uniform Spin Currents.

We propose a new mechanism and a related device concept for a robust, magnetic field tunable radio-frequency (rf) oscillator using the self oscillation of a magnetic domain wall subject to a uniform static magnetic field and a spatially non-uniform vertical dc spin current. The self oscillation of the domain wall is created as it translates periodically between two unstable positions, one being in the region where both the dc spin current and the magnetic field are present, and the other, being where only the magnetic field is present. The vertical dc spin current pushes it away from one unstable position while the magnetic field pushes it away from the other.

Spin control by application of electric current and voltage in FeCo-MgO junctions.

Efficient control and detection of spins are the most important tasks in spintronics. The current and voltage applied to a magnetic tunnel junction may exert a torque on the magnetic thin layer in the junction and cause its reversal or continuous precession. The discovery of the giant tunnelling magnetoresistance effect in ferromagnetic tunnelling junctions using an MgO barrier enabled us to obtain a large signal output from the magnetization reversal and precession.

Images of a spin-torque-driven magnetic nano-oscillator.

We present the first space- and time-resolved images of the spin-torque-induced steady-state oscillation of a magnetic vortex in a spin-valve nanostructure. We find that the vortex structure in a nanopillar is considerably more complicated than the 2D idealized structure often-assumed, which has important implications for the driving efficiency. The sense of the vortex gyration is uniquely determined by the vortex core polarity, confirming that the spin-torque acts as a source of negative damping even in such a strongly nonuniform magnetic system.

Large voltage-induced magnetic anisotropy change in a few atomic layers of iron.

In the field of spintronics, researchers have manipulated magnetization using spin-polarized currents. Another option is to use a voltage-induced symmetry change in a ferromagnetic material to cause changes in magnetization or in magnetic anisotropy. However, a significant improvement in efficiency is needed before this approach can be used in memory devices with ultralow power consumption.

Direct observation of spin-torque driven magnetization reversal through nonuniform modes.

We present time-resolved x-ray images with 30 nm spatial and 70 ps temporal resolution, which reveal details of the spatially resolved magnetization evolution in nanoscale samples of various dimensions during reversible spin-torque switching processes. Our data in conjunction with micromagnetic simulations suggest a simple unified picture of magnetic switching based on the motion of a magnetic vortex. With decreasing size of the magnetic element the path of the vortex core moves from inside to outside of the nanoelement, and the switching process evolves from a curled nonuniform to an increasingly uniform mode.

Spin-torque diode effect in magnetic tunnel junctions.

There is currently much interest in the development of 'spintronic' devices, in which harnessing the spins of electrons (rather than just their charges) is anticipated to provide new functionalities that go beyond those possible with conventional electronic devices. One widely studied example of an effect that has its roots in the electron's spin degree of freedom is the torque exerted by a spin-polarized electric current on the spin moment of a nanometre-scale magnet. This torque causes the magnetic moment to rotate at potentially useful frequencies.

Local magnetism of isolated Mo atoms at substitutional and interstitial sites in Yb metal: experiment and theory.

We have observed large 4d moments on isolated Mo atoms at substitutional and octahedral interstitial lattice sites in Yb metal, showing Curie-Weiss local susceptibility and a Korringa-like spin relaxation rate. The interstitial Mo atoms, despite strong hybridization with the Yb neighbors, show rather small Kondo temperature ( T(K) View Article and Find Full Text PDF