An international team of scientists has discovered a new route to ultra-low-power transistors using a graphene-based composite material.
As transistors are squeezed into ever smaller areas within computer chips, the semiconductor industry struggles to contain overheating in devices.
Now researchers from the University of York and Roma Tre University believe the solution lies in composite materials built from monolayers of graphene and the transition metal dichalcogenide (TMDC).They discovered these materials could be used to achieve a fine electrical control over the electron’s spin – its tiny compass needle.
The new research, published today in the journal Physical Review Letters, could lead the way to much needed low-energy consumption electronics.
Lead researcher Dr Aires Ferreira, of the University of York’s Department of Physics, said: “For many years, we have been searching for good conductors allowing efficient electrical control over the electron’s spin.
“We found this can be achieved with little effort when two-dimensional graphene is paired with certain semiconducting layered materials. Our calculations show that the application of small voltages across the graphene layer induces a net polarization of conduction spins.
“We believe that our predictions will attract substantial interest from the spintronics community. The flexible, atomically thin nature of the graphene-based structure is a major advantage for applications. Also, the presence of a semiconducting component opens up the possibility for integration with optical communication networks.”
The electron’s spin is like a tiny, point-like magnet which can point only in two directions, up or down. In materials where a major fraction of electrons’ spins is aligned, a magnetic response is produced, which can be used to encode information.
‘Spin currents’ – built from ‘up’ and ‘down’ spins flowing in opposite directions – carry no net charge, and therefore in theory, produce no heating. The control of spin information would therefore open the path towards ultra-energy-efficient computer chips.
The team of researchers showed that when a small current is passed through the graphene layer, the electrons’ spin polarize in plane due to ‘spin-orbital’ forces brought about by the proximity to the TMDC base. They also showed that the efficiency of charge-to-spin conversion can be quite high even at room temperature.
Manuel Offidani, a PhD student with York’s Department of Physics, carried out most of the complex calculations in this study. He said: “The current-induced polarization of the electron’s spin is an elegant relativistic phenomenon that arises at the interface between different materials.
“We chose graphene mainly because of its superb structural and electronic properties. In order to enhance the relativistic effects experienced by charge carriers in graphene, we investigated the possibility of matching it with recently discovered layered semiconductors.”
Professor Roberto Raimondi, who leads the spintronics group at Roma Tre University, said: “The possibility of orienting the electron spin with electrical currents is attracting a lot of attention in the spintronics community and arises generally as a consequence of specific symmetry conditions.
“As such this phenomenon represents a perfect example where fundamental and applied research go happily together. In this respect, our calculations demonstrate that graphene combined with the transition metal dichalcogenides is an ideal platform where abstract theoretical principles may find immediate application in showing the way to experimental and technological development.”
Current-induced spin polarization in non-magnetic media was first demonstrated in 2001 in semiconductors and, more recently, in metallic hetero-interfaces. Now the researchers predict that a similar effect occurs in graphene on TMDC monolayer.
Surprisingly they found that the unique character of electronic states in graphene enable charge-to-spin conversion efficiency of up to 94 per cent. This opens up the possibility of a graphene-based composite material becoming the basis for ultra-compact and greener spin-logic devices.
Dr Mirco Milletarì, a former member of the spintronics group at Roma Tre University, said: “This work follows insights gained from understanding fundamental laws that enabled us to envisage systems where the efficiency of charge-to-spin conversion can be optimal for technological applications. In particular, the much needed low-energy consumption electronics that will improve durability and performances of future devices.”
The Latest on: Ultra-low-power transistors
- Tubes Versus Solid-State Audio Amps—The Last Word (Or “House Of Fire,” Part 2)on June 21, 2020 at 5:01 pm
Part 2 concentrates on the difference between transistors—MOSFETs and bipolar ... A family of minuscule, ultra-low-power comparators is offered in various input and output configurations to ...
- Ramp Generator Uses Microcontroller Emulation Of Unijunction Transistoron June 21, 2020 at 5:01 pm
Unijunction transistors (UJTs ... A family of minuscule, ultra-low-power comparators is offered in various input and output configurations to easily interface with different sources and loads.
- A 4-bit Computer From Discrete Transistorson June 18, 2020 at 5:00 pm
he’s building a computer from discrete transistors. Building a computer from individual components without chips isn’t something new – Minecraft players who aren’t into cheaty command ...
- Engineers advance insights on black phosphorus as a material for future ultra-low power flexible electronicson June 16, 2020 at 5:00 pm
Engineers advance insights on black phosphorus as a material for future ultra-low power flexible electronics June 17, 2020 , Vanderbilt University Credit: ACS ...
- SuVolta Announces Speed-Power Benefits of Transistor Technology Validated in ARM Processoron June 14, 2020 at 5:00 pm
ARM Says Innovative Ultra-Low Power Technology Will Be Vital to Ensure ARM Remains ... gains with associated power reduction in an ARM Cortex-M0 processor built using transistor technology from ...
- Op Amps Before Transistors: A 600V Vacuum Tube Monsteron June 13, 2020 at 5:00 pm
Op amps. Often the first thing that many learn about when beginning the journey into analog electronics, they’re used in countless ways in an overwhelmingly large array of circuits. When we ...
- Diodes Inc. Now A Better Near-Term Bet Than Broadcomon June 13, 2020 at 8:08 am
Not for a long-term hold; this may be a three-month or less position while DIOD catches up with other semiconductor stocks. DIOD’s odds-on prospect has a histor ...
- Breaking new energy efficiency records with advanced power management platformon June 8, 2020 at 4:37 am
1: Ultra-Low Power microcontroller market evolution 2019-2024 Major ... Using high Vth cells is one way to obtain decent figures, however the use of thick oxide transistors is probably the most ...
- ‘Microchip Technology Caldicot’ in Wales works on nano-relay logic projecton June 8, 2020 at 4:15 am
Microchip has changed the name of its UK subsidiary that is working on nano-relay-based logic and memory for an EU ultra-low-power computing and memory ... electro-mechanical relays instead of ...
- Kilopass Announces Breakthrough Memory Technology for IoT Deviceson June 2, 2020 at 5:00 pm
Kilopass has pioneered the antifuse One-Time-Programmable (OTP) eNVM technologies since 2001, including all variants of 1 transistor (1T), 1.5T ... as low as 0.75V that are used in the emerging ...
via Google News and Bing News