Spintronics News - Page 1

Researchers from the Madrid Institute for Advanced Studies in Nanoscience (IMDEA) and the University of Sevilla have measured for the first time the electrical conductivity of a single carbon nanotube with spin-crosslinked molecules inside it.

Iron-based SCO molecules encapsulated in a single carbon nanotube. Credit: Nature Communications

Magnetic molecules could add a new twist to conventional electronics. In particular, spin-crossover (SCO) molecules belong to a family of zero-dimensional (0D) functional units that display a radical spin switch triggered by an electro-structural change activatable by external stimulus such as light, pressure or temperature. The spin switch confers SCO molecules excellent capabilities and functionalities for implementation in nano-electronics. However, their insulating character has so far prevented these molecules from being fully exploited. Several groups have embedded SCO molecules into matrices of conductive materials but the results have not been fully compatible with the requirements of nanoscale devices.

A team of researchers from the National Renewable Energy Laboratory (NREL) and the University of Utah has developed a new type of LEDs that utilizes spintronics without needing a magnetic field, magnetic materials or cryogenic temperatures.

“The companies that make LEDs or TV and computer displays don’t want to deal with magnetic fields and magnetic materials. It’s heavy and expensive to do it,” said Valy Vardeny, distinguished professor of physics and astronomy at the University of Utah. “Here, chiral molecules are self-assembled into standing arrays, like soldiers, that actively spin polarize the injected electrons, which subsequently lead to circularly polarized light emission. With no magnetic field, expensive ferromagnets and with no need for extremely low temperatures. Those are no-nos for the industry.”

An international research team, led by the University of Tsukuba, has used electron spin resonance (ESR) to monitor the number and location of unpaired spins going through a molybdenum disulfide transistor. ESR uses the same physical principle as the MRI machines that create medical images. The spins are subject to a very strong magnetic field, which creates an energy difference between electrons with spins aligned and anti-aligned with the field. The absorbance of photons that match this energy gap can be measured to determine the presence of unpaired electron spins.

15 1 Share Email Home Physics Condensed Matter MARCH 5, 2021 Taking 2-D materials for a spin by University of Tsukuba Schematic diagram of the MoS2 transistor in an ESR sample tube. Credit: University of Tsukuba

The experiment required the sample to be cooled to just four degrees above absolute zero, and the transistor to be in operation while the spins are being measured. "The ESR signals were measured simultaneously with the drain and gate currents," corresponding author Professor Kazuhiro Marumoto says. "Theoretical calculations further identified the origins of the spins," coauthor Professor Małgorzata Wierzbowska says. Molybdenum disulfide was used because its atoms naturally form a nearly flat two-dimensional structure. The molybdenum atoms form a plane with a layer of sulfide ions above and below.

An international research team, led by the University at Buffalo, has reported an advancement that could help give graphene magnetic properties. The researchers describe in their work how they paired a magnet with graphene, and induced what they describe as “artificial magnetic texture” in the nonmagnetic material. This achievement may, according to the researchers, push forward the spintronics field.

The image shows eight electrodes around a 20-nanometer-thick magnet (white rectangle) and graphene (white dotted line). Credit: University at Buffalo.

“Independent of each other, graphene and spintronics each possess incredible potential to fundamentally change many aspects of business and society. But if you can blend the two together, the synergistic effects are likely to be something this world hasn’t yet seen,” says lead author Nargess Arabchigavkani, who performed the research as a PhD candidate at UB and is now a postdoctoral research associate at SUNY Polytechnic Institute.

A new theory by Rice University scientists could boost the field of spintronics. Materials theorist Boris Yakobson and graduate student Sunny Gupta at Rice’s Brown School of Engineering describe the mechanism behind Rashba splitting, an effect seen in crystal compounds that can influence their electrons’ “up” or “down” spin states, analogous to “on” or “off” in common transistors.

The left shows the crystal structure of a MoTe2

The Rice model characterizes single layers to predict heteropairs — two-dimensional bilayers — that enable large Rashba splitting. These would make it possible to control the spin of enough electrons to make room-temperature spin transistors, a far more advanced version of common transistors that rely on electric current.

A research team at NTU’s School of Physical and Mathematical Sciences and School of Materials Science and Engineering, led by Associate Professor Gao Weibo, together with colleagues from the Singapore University of Technology and Design, has won substantial funding from Singapore’s National Research Foundation to develop high-performance spintronics devices.

The five-year programme, called “The next generation of spintronics with 2D heterostructures”, aims to develop spintronics devices based on next-generation van der Waals materials, which are strongly bonded two-dimensional (2D) layers of materials that are bound in the third dimension through weaker van der Waals forces.

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.