Image Credit: mkfilm/Shutterstock.com
Spinning a magnetic property of electrons and other fundamental particles promises to play an essential role in the future of data storage and transmission. Two new pieces of research investigate this tiny phenomenon that could have huge implications for computing.
Spintronics has the potential to deliver staggering high speed, high-density computing by providing hardware with a significant memory boost.
Spintronic computing may have taken a significant step towards realization this week, with the unveiling of a research paper that could reduce the power demands of such technology. Meanwhile, a separate team of researchers has investigated the potential of spintronics in generating high-efficiency and hydroelectric power generation that could be an essential step in improving nanometre scale tech.
The research from separate teams at institutions, including the University of Exeter and the Japan Science and Technology Agency, published in the journals Physical Review Letters and Nature Communications respectively, offer novel techniques to reduce the power demands of spintronic computing further.
Spintronics uses the spin of an electron — a fundamental property that is best considered to be a magnetic phenomenon— instead of its charge to hold information. We are all familiar with the flow of electrons’ charges being described as an electric current, but the spin of electrons can flow similarly, a phenomenon unsurprisingly called spin current.
The use of spin current already makes spintronics a low-power mode of computation, but these teams believe they can further improve on this efficiency. In the process, the separate crews of scientists take very different yet equally valid routes to energy efficiency.
Traveling by Tunnelling
An international team of researchers, led by scientists from the University of Exeter collaborating with Universities of Oxford, California Berkeley, and the Advanced and Diamond Light Sources, believes that their research, documented in Physical Review Letters, constitutes a significant breakthrough in the energy efficiency of spintronic data technology.
The team’s research builds upon the recent discovery that some antiferromagnetic materials — substances with a magnetic structure in which magnetic moments align in an antiparallel formation — can be electrically insulating and exceptional conductors of spin currents.
The researchers found that in experiments with nickel oxide (NiO), this basic metal oxide chemical compound and antiferromagnetic material could transmit and, under certain conditions, amplify alternating (AC) spin currents.
The paper reveals that evanescent spin waves mediate the spin current in thin layers of NiO, an effect that is analogous to quantum tunneling, the phenomenon by which particles are found in classically forbidden areas that they should use insufficient energy to reach.
The team was also able to demonstrate that the transfer of AC spin current using thin layers of NiO can be conducted at room temperature. This is an essential advantage over other quantum computers that rely on remaining extremely cold to prevent quantum decoherence and the loss of information.
This is the first real confirmation of the evanescent spin-wave mechanism and the fact that transfers of angular momentum between the spins of different electrons can occur in NiO films.
As well as opening the door to the construction of the nanoscale spin current amplifiers, the discovery also has implications for wireless communications.
Going with the Flow
Like their counterparts at the University of Exeter, the team from RATO Saitoh Spin Quantum Rectification Project in the JST Strategic Basic Research Programs produced research, this time in Nature Communications, regarding spin currents.
Rather than investigating the flow of such currents through antiferromagnetic material, this latter team of researchers delved into the possibility of hydrodynamic power generation using these currents in micrometer-sized channels.
The team discovered that when moving through a microchannel, the spin current takes the form of what is known as a ‘Laminar flow.’ In this small channel, a low-velocity flow finds viscosity the dominant factor determining its behavior, creating a regular flow in layers along the length-axis of the channel and a micro-vortex liquid motion evenly distributed through the channel.
The properties of the Laminar flow described above lend themselves to effective miniaturization and a significant boost in power generation. The team’s results also show that in the Laminar flow region, energy efficiency is increased by a magnitude of 100,000 times. This efficiency is increased as the flow size is decreased.
One massive advantage of this form of power generation is the elimination of the need for additional and unwieldy equipment such as coils and loops that more traditional methods such as hydroelectric power generation and magnetohydrodynamic power generation require.
This means this new modality of power generation could be of specific use in nanofluidic devices — technology that relies on liquids flowing through nanometre scale channels — particularly cooling mechanisms that rely on liquid metal flow, including semiconductors vital in computing.
Read more: Nanolithography systems for the fabrication of nanometer-scale structures
References and Further Reading
Dabrowski. M, Nakano. T, Burn. D. M, et al, , ‘Coherent Transfer of Spin Angular Momentum by Evanescent Spin Waves within Antiferromagnetic NiO,’ Physical Review Letters, https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.124.217201.
Takahashi. R, Chudo. H, Matsuo. M, et al, , ‘Giant spin hydrodynamic generation in laminar flow,’ https://www.nature.com/articles/s41467-020-16753-0.