Research / Technical - Page 15

Yttrium iron garnet is a material which has special magnetic properties. A new process, developed by physicists at Martin Luther University Halle-Wittenberg (MLU), allows for it to be transferred to any material. The new method could advance the production of smaller, faster and more energy-efficient components for data storage and information processing.

Magnetic materials play a major role in the development of new storage and information technologies. Magnonics is an emerging field of research that studies spin waves in crystalline layers. Spin is a type of intrinsic angular momentum of a particle that generates a magnetic moment. The deflection of the spin can propagate waves in a solid body. "In magnonic components, electrons would not have to move to process information, which means they would consume much less energy," explains Professor Georg Schmidt from the Institute of Physics at MLU. This would also make them smaller and faster than previous technologies.

Some of the latest advances in spintronics are based on nanometric thin film structures with perpendicular magnetic anisotropy in which the spin currents are used to produce changes in the magnetization of a magnetic layer. This effect is known as spin-orbit torque (SOT) and can be enhanced by suitably engineering multilayer stacks composed by alternated magnetic/non-magnetic metals. The typical structures employed to manipulate the magnetization via SOT are multilayers whose basic constituent is a ferromagnetic layer adjacent to heavy metal(s), which confer large spin-orbit coupling and promote the perpendicular magnetic anisotropy. These systems are the basic elements for spin-orbit torque magnetization switching, used in the next generation of magnetoresistive random access memory (MRAM) devices.

The SpinOrbitronics research team, guided by Dr. Paolo Perna at IMDEA Nanociencia, have observed the emergence of an interfacially enabled increase of the spin-orbit torque when an ultrathin Cu interlayer is inserted between Co and Pt in symmetric Pt/Co/Pt trilayer, in which the effective spin-orbit torque is expected to vanish. The enhancement of SOT is accompanied by a reduction of the spin-Hall magnetoresistance, indicating that the spin memory loss effect in the Co/Cu and Cu/Pt interfaces is responsible of both enhanced SOT and reduction in the spin-Hall magnetoresistance.

A multi-institutional team which included researchers from the Department of Energy's Oak Ridge National Laboratory, the University of Tennessee, Purdue University and D-Wave Systems, succeeded in generating accurate results from materials science simulations on a quantum computer that can be verified with neutron scattering experiments and other practical techniques.

The researchers used the power of quantum annealing, a form of quantum computing, by embedding an existing model into a quantum computer. Their unique approach proved that quantum resources are capable of studying the magnetic structure and properties of materials, which could lead to a better understanding of spin liquids, spin ices and other novel phases of matter useful for data storage and spintronics applications.

Antiferromagnetic (AFM) spintronics are devices or components for electronics that couple a flowing current of charge to the ordered spin 'texture' of specific materials. The successful development of AFM spintronics could have important implications, as it could lead to the creation of devices or components that surpass Moore's law. But it seems that finding materials with the exact characteristics necessary to fabricate AFM spintronics is highly challenging.

Researchers at the Lawrence Berkeley National Laboratory, UC Berkeley and the National High Magnetic Field Laboratory in Tallahassee have recently identified a new quantum material (Fe_1/3 + _δNbS₂) that could be used to fabricate AFM spintronic devices. In their most recent papers, they demonstrated the feasibility of using this material for two AFM spintronics applications.

Researchers at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory and Yale University have demonstrated the ability to control spin dynamics in magnetic materials by altering their thickness. The new study could lead to smaller, more energy-efficient electronic devices.

“Instead of searching for different materials that share the right frequencies, we can now alter the thickness of a single material—iron, in this case—to find a magnetic medium that will enable the transfer of information across a device,” said Brookhaven physicist and principal investigator Valentina Bisogni.

Researchers have recently demonstrated the long-range transport of magnetic hedgehogs, 3D topological spin structures that are often observed in common magnets. Their work could have important implications for the development of spintronic devices.

Nonlocal transport measurement of hedgehog currents in a three-dimensional insulating magnet. Image from article

Magnetic insulators are a class of materials widely used worldwide, mainly due to their ability to conduct electrical charges. Just like metals conduct electrical charges, magnetic insulators can conduct spins. Nonetheless, as spins are rarely conserved in materials and tend to disappear over long distances, so far, using magnetic insulators to achieve long-range transport has proved highly challenging.

A research team, led by Dr. Kim Kyoung-Whan at the Center for Spintronics of the Korea Institute of Science and Technology (KIST), has proposed a new principle which could give a boost to spin memory devices.

Conventional memory devices are classified into volatile memories, such as RAM, that can read and write data quickly, and non-volatile memories, such as hard-disk, on which data are maintained even when the power is off. In recent years, related academic and industrial fields have been working to accelerate the development of next-generation memory that is fast and capable of maintaining data even when the power is off.

Researchers at the Czech Academy of Sciences, Charles University in Prague, ETH Zurich and other universities in Europe recently introduced a method to achieve the quenching of antiferromagnets into high resistivity states by applying either electrical or ultrashort optical pulses. This strategy could open interesting new avenues for the development of spintronic devices based on antiferromagnets.

Antiferromagnetism is a type of magnetism in which parallel but opposing spins occur spontaneously within a material. Antiferromagnets, materials that exhibit antiferromagnetism, have advantageous characteristics that make them particularly promising for fabricating spintronic devices. Due to their ultrafast nature, their insensitivity to external magnetic fields and their lack of magnetic stray fields, antiferromagnets could be particularly desirable for the development of spintronic devices. However, despite their advantages, most simple antiferromagnets have weak readout magnetoresistivity signals. Moreover, so far scientists have been unable to change the magnetic order of antiferromagnets using optical techniques, which could ultimately allow device engineers to exploit these materials' ultrafast nature.

University of Tokyo researchers have created a material that confines electrons in one dimension in the form of a special bismuth-based crystal known as a high-order topological insulator.

To create spintronic devices, new materials need to be designed that take advantage of quantum behaviors not seen in everyday life. For spintronic applications, a new kind of electronic material is required - a topological insulator. It differs from other materials by insulating throughout its bulk, but conducting only along its surface. And what it conducts is not the flow of electrons themselves, but a property of them known as their spin or angular momentum.

A team of researchers has discovered a mechanism in antiferromagnets that could be useful for spintronic devices. They theoretically and experimentally demonstrated that one of the magnetization torques arising from optically driven excitations has a much stronger influence on spin orientation than previously given credit for. The result of their study could provide a new and efficient mechanism for manipulating spin. which has so far proven to be a challenging task.

Antiferromagnetic materials (AFMs) are good candidates for spintronics because they are resistant to external magnetic fields and allow for switching spin values in timescales of picoseconds. One promising strategy to manipulate spin orientation in AFMs is using an optical laser to create extremely short-lived magnetic field pulses, a phenomenon known as the inverse Faraday effect (IFE). Although the IFE in AFMs generates two very distinct types of torque (rotational force) on their magnetization, it now seems the most important of the two has been somewhat neglected in research.