Researchers Make Strides in “Spintronics” (Spin Electronics)January 26, 2020 by Cabe Atwell
Scientists have ramped-up research in "spintronics" (spin electronics) to make breakthroughs in new quantum materials, stable spin states, and new devices.
Research in spintronics (spin electronics) has been on the rise over the last decade. According to a 2020-2025 forecast report on spintronics from Mordor Intelligence, the market share commanded by the technology is expected to grow from $3.62 billion (in 2019) to $26 billion in the next five years.
Spintronics is the intrinsic spin of an electron in its associated magnetic moment or the magnetic strength and orientation of an object that produces a magnetic field in addition to its electric charge.
Researchers from the University of Utah explain, "If you’ve ever done the old science experiment of turning a nail into a magnet by repeatedly dragging a magnet along its length, then you’ve already dabbled in spintronics. The magnet transfers information to the nail."
Scientists have explored this new field of applied physics to advance electronics in solid-state devices using an electron’s spin to carry information instead of its charge.
Electronics manufacturers have already applied spintronics in one form or another to produce read-heads on magnetic hard drives, MRAM (Magnetoresistive Random-Access Memory), and magnetic sensors. Spintronics offers increased data processing speed, decreased power consumption, and greater densities over current semiconductor devices.
In recent years, scientists have ramped-up their research into this relatively new branch of physics to make breakthroughs using new materials, stable spin states, and new devices, including a new type of LED and spin valve.
New Material for Antiferromagnetic Spintronics and Quantum Tech
Researchers from Technische Universitat Dresden and other academic institutions have discovered a new material they state has potential for applications in antiferromagnetic spintronics and quantum technologies.
The material, known as manganese-bismuth telluride (MnBi2Te4), has a pair of properties that favor spintronics, including magnetism and superconductivity, making it a great material for information processing, computing, sensors, and more.
TU Dresden researchers discover a new material that shows promise for antiferromagnetic spintronics and quantum technologies. Image used courtesy of Technische Universitat Dresden
Because quantum materials usually require specific conditions, such as low temperatures, strong magnetic fields, and high pressures, scientists continuously research other methods of producing those materials without strict requirements.
As a result, the researchers developed a novel crystal-growing technique to produce the first intrinsically magnetic topological material (MTI), which offers quasi-particles and quantum phenomena within the material.
The new MnBi2Te4 MTI crystal features an edge state on its surface that may realize a quantized Hall conductivity without the need for a strong external magnetic field. This makes it a useful material for antiferromagnetic spintronics as well as two-dimensional ferromagnets.
The researchers have already devised an optimized synthesis protocol that makes it easier to produce the material, and have found there are more structural derivatives to push MTIs, increasing its application potential.
Molecular Spintronics Pave Way for Miniaturization
While some scientists have made advancements in new materials for spintronic applications, others have made progress in spintronic stability by gaining control of spin states of individual molecules.
Chemists and physicists from Kiel University have designed, deposited, and operated single molecular spin switches on surfaces, enabling stable spin states that don’t lose their functionality when absorbed into said surfaces. The researchers state the new molecules remain stable for at least several days, which is unprecedented in the field of spintronics.
The secret lies in a design trick that resembles flip-flops (0s and 1s) in electronic circuits found in CPUs, which is realized by looping the output signal back into the input.
Intermolecular cooperation. Chemists from Kiel University have designed new molecules that operate single molecular spin switches on surfaces, which increases their stability and advances the goal of miniaturizing of spintronics. Image (modified) used courtesy of Kiel University
The new molecules feature three properties that are tied to each other in that feedback loop, including their shape (flat or planar), the proximity of two subunits (coordination, yes or no), and their spin state (high-spin/low-spin).
This allows the molecules to be locked in either state; when deposited on a silver surface, the switches arrange themselves into highly-ordered arrays.
Each molecule in the array can be addressed separately using a scanning tunneling microscope and switched between states using positive or negative voltage. The new spin switch in a single molecule could replace the transistors and resistors found in current electronic components, which makes it a giant step for miniaturizing spintronics.
A "Miracle Mineral" for Spintronic Devices
Materials play an important role in developing spintronic devices, and while some scientists have made great strides in producing new materials for spin applications, others have innovated electronics devices using substances that were discovered over a century ago.
Perovskites (named after Russian mineralogist L.A. Perovski who discovered the material in 1839) are classified as any material that features the same crystalline makeup as calcium titanium oxide.
While perovskite has been around for ages, its value has only become prominent during the last ten years as companies have used its crystalline structure for manufacturing energy-efficient solar panels.
Researchers from the University of Utah have designed a pair of spintronic devices that use a class of perovskite known as an organic-inorganic hybrid, which offers a large spin-orbit coupling.
The first devices are a spintronic-based green LED, which works in the same fashion as a traditional LED that uses electrons and diodes to emit light. Only, the spintronic version features a magnetic electrode and electron holes polarized to receive electrons with a certain spin.
Wavelengths of light emitted from the spintronic LED. University of Utah researchers have created two spintronic devices using a perovskite material, including an LED and spin valve. Image used courtesy of the University of Utah
The LED illuminates with electroluminescence in the green wavelength of the color spectrum, which proves the magnetic electrode successfully transferred spin-polarized electrons through the perovskite material.
The second device the researchers created is known as a spin valve, which uses an external magnetic field to flip magnetic materials in the valve between an open low-resistance state to a closed high-resistance state.
Similar devices can be found in a modern hard drive. Only, the spintronic version can have spin injected into the device and cause it to precess (change the orientation of the rotational access) or wobble using magnetic manipulation.
Those abilities allow spintronics to be incorporated into data storage devices. They can also be used for calculation, meaning it can be used to create super-fast, highly-efficient CPUs.
Researchers at Mordor Intelligence predict that researchers will continue to find ways to deploy spintronic data storage for a broad range of applications, including use in electric vehicles (EVs) and industrial motors.
Have you worked on projects that directly involved spintronics? What was your experience? Share your thoughts in the comments below.