Recent Spintronic News - Page 2

Researchers use ultrashort laser pulses to trigger a spin-aligned electron flow on the few-femtosecond timescale—opening up a possible path toward faster spintronic devices.

Spintronics technology requires a rapid, controlled way to create spin currents. To that end, the researchers have demonstrated that short laser pulses can create spin currents within a few femtoseconds (10–15 s) — about 30 times faster than previous techniques. The method, they believe, should provide a more flexible and precise way to generate spin currents by taking advantage of the control that physicists have over laser light.

Researchers at King Abdullah University of Science and Technology (KAUST) and Khalifa University of Science and Technology have investigated the transmission, tunneling magnetoresistance ratio and spin injection efficiency of bilayer LaI₂ using a combination of first-principles calculations and the non-equilibrium Green’s function method. 

Multilayer graphene electrodes were used by the team, to build a magnetic tunnel junction with bilayer LaI₂ as ferromagnetic barrier. The magnetic tunnel junction reportedly proved to be a perfect spin filter device with an impressive tunneling magnetoresistance ratio of 653% under a bias of 0.1 V and a still excellent performance in a wide bias range. The team said that in combination with the obtained high spin injection efficiency, this could hold great potential from an application point of view.

Researchers from the University of California - Riverside, National Institute of Standards and Technology, Massachusetts Institute of Technology and Rigaku Americas have developed a new superconductor material that could potentially be used in quantum computing and be a candidate 'topological superconductor.'

A topological superconductor uses a delocalized state of an electron or hole (a hole behaves like an electron with positive charge) to carry quantum information and process data in a robust manner. The researchers reported in their recent work that they combined trigonal tellurium with a surface state superconductor generated at the surface of a thin film of gold. Trigonal tellurium is a chiral material, which means it cannot be superimposed on its mirror image, like our left and right hands. Trigonal tellurium is also non-magnetic. Nonetheless, the researchers observed quantum states at the interface that host well-defined spin polarization. The spin polarization allows the excitations to be potentially used for creating a spin quantum bit -- or qubit.

Researchers from ETH Zurich recently developed a method to control the quantum states of single electron spins using spin-polarized currents, which could enhance quantum computing technologies. The new technique offers more precise, localized control compared to traditional methods using electromagnetic fields, potentially improving the manipulation of quantum states in devices like qubits. 

Control over quantum systems is typically achieved by time-dependent electric or magnetic fields. Alternatively, electronic spins can be controlled by spin-polarized currents. In their recent work, the team demonstrated coherent driving of a single spin by a radiofrequency spin-polarized current injected from the tip of a scanning tunneling microscope into an organic molecule. With the excitation of electron paramagnetic resonance, the scientists established dynamic control of single spins by spin torque using a local electric current. In addition, their work highlights the dissipative action of the spin-transfer torque, in contrast to the nondissipative action of the magnetic field, which allows for the manipulation of individual spins based on controlled decoherence.

Researchers at India's Institute of Nano Science and Technology (INST), an autonomous research institution of Department of Science and Technology (DST), recently produced a transparent conducting interface between two insulating materials with room temperature spin polarized electron gas, which allows for see-through devices with efficient spin currents. 

Prof. Suvankar Chakraverty and his group at INST have produced a 2D Electron Gas (2DEG) with room temperature spin polarization at the interface composed of chemicals LaFeO₃ and SrTiO₃. They grew super lattices and hetero structures of oxide materials to realize new and exotic two-dimensional electron gas at the interface of two insulating oxides that could be useful for next generation quantum devices.

Researchers at the University of Tübingen, Helmholtz-Zentrum Berlin, University of Nebraska and Trinity College have used a very thin layer of radicals, 10000 times thinner than a human hair, to coat a ferromagnetic material, polycrystalline cobalt, to change the magnetic properties of cobalt at the junction with the radicals.

Purely organic radicals are a family of molecules composed only of light elements, such as carbon, nitrogen, and oxygen. They are transparent, light, and flexible materials. They promise lower costs of production and sustainable, and recyclable chemistry. These radicals are organic molecules that carry an unpaired electron, i.e., they are materials with permanent magnetic properties. They must be used as a film in a device, i.e., the radical molecules cover a substrate such as a metal surface, forming a coating. 

Researchers have developed "somersaulting" spin qubits for universal quantum logic. This achievement may enable efficient control of large semiconductor qubit arrays. This is based on two studies published by the research group: a demonstration of "hopping" spins in Nature Communications and their work on "somersaulting" spins in Science. 

In 1998, Loss and DiVincenzo published the seminal work ‘quantum computation with quantum dots’. In their original work, hopping of spins was proposed as a basis for qubit logic, but an experimental implementation remained lacking. After more than 20 years, experiments have caught up with theory. Researchers at QuTech—a collaboration between the TU Delft and TNO—have demonstrated that the original ‘hopping gates’ are indeed possible, with state-of-the-art performance.

Researchers from the Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Sorbonne Université CNRS, INRS-EMT, FERMI, Uppsala University, University of York and University of Hull have developed a non-thermal method to alter magnetization using XUV radiation, utilizing the inverse Faraday effect in an iron-gadolinium alloy. This approach enables significant magnetization changes without the usual thermal effects, promising enhancements in ultrafast magnetism technologies. 

Intense laser pulses can be used to manipulate or even switch the magnetization orientation of a material on extremely short time scales. Typically, such effects are thermally induced, as the absorbed laser energy heats up the material very rapidly, causing an ultrafast perturbation of the magnetic order. The research team has now demonstrated an effective non-thermal approach of generating large magnetization changes. By exposing a ferrimagnetic iron-gadolinium alloy to circularly polarized pulses of extreme ultraviolet (XUV) radiation, they could reveal a particularly strong magnetic response depending on the handedness of the incoming XUV light burst (left- or right-circular polarization).

While the field of spintronics tries to leverage the spin angular momentum of electrons to develop new technologies, these particles' orbital momentum has so far been rarely considered. Currently, generating an orbital current (i.e., a flow of orbital angular momentum) remains far more challenging than generating a spin current. Nonetheless, approaches to successfully leveraging the orbital angular momentum of electrons could open the possibility for the development of a new class of devices called orbitronics.

Researchers at Japan's Keio University and Germany's Johannes Gutenberg University have reported the successful generation of an orbital current from magnetization dynamics, a phenomenon called orbital pumping. Their outlines a promising approach that could allow engineers to develop new technologies leveraging the orbital angular momentum of electrons.

Researchers from National Renewable Energy Laboratory (NREL), University of Utah, Université de Lorraine CNRS and University of Colorado Boulder have improved upon their previous work, that included incorporating a perovskite layer that allowed the creation of a new type of polarized light-emitting diode (LED) that emits spin-controlled photons at room temperature without the use of magnetic fields or ferromagnetic contacts. In their latest work, they have gone a step further by integrating a III-V semiconductor optoelectronic structure with a chiral halide perovskite semiconductor.

The team transformed an existing commercialized LED into one that also controls the spin of electrons. The results could provide a pathway toward transforming modern optoelectronics, a field that relies on the control of light and encompasses LEDs, solar cells, and telecommunications lasers, among other devices.