Recent experimental and theoretical studies have revealed that orbital transport could provide an alternative mechanism for efficient spin manipulation in the form of orbital torque. This study presents experimental studies on charge-to-orbital conversion and orbital torque in CoFe/Cu/Oxide heterostructures. In these systems, the charge-to-orbital conversion mainly occurs at the Cu/Oxide interface via the orbital Rashba-Edelstein effect. Although we observe sizeable orbital torque in all structures, the torque efficiency varies more than twice depending on the Oxide. Moreover, the torque efficiency can be changed by annealing and/or oxygen incorporation by a maximum of three times.
Strong coupling between light and excitations of a two-dimensional electron gas (2DEG) are important to both pure physics and to the development of future photonic nanotechnologies. Studying the relationship between spin polarisation of a 2DEG in monolayer semiconductor MoSe2, and resultant light-matter interactions modified by a zero-dimensional optical microcavity, finds the robust spin-susceptibility of the 2DEG simultaneously enhances/supresses trion-polariton formation in opposite photon helicities. This leads to optical non-linearities arising from the highly non-linear behaviour of the valley-specific strong light-matter coupling regime and allowing all-optical tuning of the enhanced polaritonic Zeeman splitting from 4 to more than 10 meV.
https://www.nature.com/articles/s41566-022-01025-8
KEYWORDS: Ferromagnetics, Bismuth, System on a chip, Metals, Electron beams, Silicon, Resistance, Magnetism, Spintronics, Current controlled current source
Spin-charge conversion induced by spin-orbit coupling (SOC) is attractive topic for alternative magnetization manipulation and involved various novel phenomena. Particularly Bi-based structure draws interest due to its large Rashba-Edelstein effect (REE) at interface between non-magnetic metal and Bi [1]. A recent report showed that spin-to-charge current conversion becomes more efficient when Bi2O3 is employed on behalf of the Bi [2]. Here we report novel type of magnetoresistance (MR) in Co25Fe75/Cu/Bi2O3 multilayer. This novel MR comes from conversion between spin and charge current at Cu/Bi2O3 interface, and distinctive spin transfer torque dependent on magnetization of the ferromagnetic Co25Fe75 layer.
A Co25Fe75 (5)/Cu (0-30)/Bi2O3 (20) (unit:nm) multilayer was deposited with electron beam evaporation on shadow masked Si substrate. Hall bar shaped shadow mask was patterned with photo-lithography method. The MR measurement was performed via 4-point probe method with changing magnitude or angle of external field. Note that external field for angle dependent measurement was 6 T to make sure complete saturation of ferromagnetic layer. We found characteristic resistance drop when the magnetization of ferromagnetic layer is parallel to magnetic direction of spin accumulation, which is similar to spin Hall magnetoresistance (SMR) [3,4]. Further discussion will be given.
[1] J. C. Rojas Sanchez et al. Nature Comm. 4, 2944 (2013).
[2] S. Karube et al. Appl. Phys. Express. 9, 03301 (2016).
[3] H. Nakayama et al. Phys. Rev. Lett. 110, 206601 (2013).
[4] J. Kim et al. Phys. Rev. Lett. (in press).
A spin current carries spin angular momentum in a spintronics device. Its interaction with a magnetic nanostructure not only gives rise to spin-dependent transport but also excites dynamics in the magnetic state. Unlike the spin-polarized electrical current, a pure spin current is useful for both fundamental and applied research because neither Oersted fields nor electrical current-related spurious effects are produced. Nonlocal electrical spin injection is a feasible way to produce the pure spin current. Here we demonstrate that the nonlocal spin valve signal is increased by an order of magnitude by improving the interface quality in a new device structure using a clean, in situ fabrication process. The generated pure spin current enables the magnetization reversal of a nanomagnet as efficiently as electrical current-induced magnetization switching. These results will open the door towards the realization of a pure-spin-current-driven device.
We investigate the magnetization dynamics induced by a current pulse in Permalloy nanowires by means of Lorentz microscopy and electron holography, together with simultaneous transport measurements. A variety of magnetization dynamics is observed below the Curie temperature. Local transformation, displacement of magnetic domain wall and nucleation and annihilation of magnetic domain, i.e. magnetization reversal are presented as a function of current density flowing into the wire and wire resistance. Shift of threshold current densities for domain wall displacement and magnetization reversal when changing current pulse duration and thermal conductance of the sample supports that observed behavior of magnetic domains and domain walls is associated with the spin transfer torque and thermal excitation. For the well-controlled magnetization reversal, we microscopically demonstrate that applying small in-plane magnetic field is very effective to controllably nucleate and erase the magnetic domain using a current pulse. Stochastic nature of the magnetization reversal due to spin-wave and thermal excitation in the absence of magnetic field completely disappears and turns into deterministic in the presence of small magnetic field, which enables the magnetization reversal control using current.
We report on the development of an analytical theory and a method of experimental observation of dynamic properties of magnetic vortices excited in cylindrical ferromagnetic discs magnetostatically coupled into arrays. The theory, based on Thiele's equation of motion and the approximative rigid-vortex model, enables us to determine the eigenfrequencies of the vortices' harmonic oscillation within pairs [J. Shibata et al., Phys. Rev. B 67, 224404 (2003)] and large arrays [J. Shibata and Y. Otani, Phys. Rev. B 70, 012404 (2004)] of the discs, the latter being a proposal to design a new type of artificial crystals with magnonic band structures. Then we briefly describe the basic principles of our time-resolved Kerr microscope and show the capabilities of our method to detect all the features studied theoretically. Finally we present an experimental example of observation of the dynamic evolution of short-pulse magnetic field excitation of a vortex weakly coupled within an array of cylindrical Permalloy discs.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.