On investigating the electron spin g factor in graphene, Researchers discovered that, this factor is surprisingly insensitive to external effects such as mobility, density and charge carrier type.
The g factor is a key parameter that defines the spin properties of electrons in a material, with important implications in spintronic applications.
Electron Spin Resonance (ESR)
The Researchers’ findings were reported in Physical Review Letters. The scientific team from the University of Wisconsin-Madison, University of Hamburg and Graphenea used ESR (electron spin resonance) to identify spin flips in monolayer graphene, whilst operating the device in a field-effect transistor configuration for density, charge carrier type and mobility tuning.
The Researchers were surprised to find that g is constant at a value of 1.95 in spite of external tuning, as it suggests that the coupling of spin to the orbital degree of freedom of the electrons in graphene is inherent. When developing any graphene-based spin-logic device, this finding will need to be considered because the g factor impacts all spin behavior, such as spin lifetime.
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Figure 1. The graphene g-factor is constant against changing external factors, such as carrier density. Copyright APS, Phys. Rev. Lett. 119, 066802 (2017).
Spintronics
Spintronics is a developing technology that, compared to electronics on which all the devices depend, exploits electron spin rather than shuttling charged carriers across devices. Similar to the “0” and “1” bit in digital electronics, electron spin can have two states – “up” and “down”. When compared to traditional electronics, manipulation of spin instead of (or in addition to) charge has numerous advantages.
Less energy is required to change spin than to produce a current, which means spintronic devices will generate less heat and last longer than electronic devices. Spin states can be rapidly set, enabling faster computing, and the state remains fixed, producing a long-term memory device. Actually, spin-based memory is already being used in contemporary magnetic hard drives.
Conclusion
Graphene is the perfect material for spintronics. It has high mobility, weak hyperfine coupling and small spin-orbit coupling, keeping the electron spins coherent over microns, sufficient to build spintronic platforms and devices.
Recently, Researchers illustrated a room-temperature spin transistor from graphene earlier this year. Other spin-logic devices will feature transistors, rewritable microchips, semiconductor nanoparticles, magnetic sensors and logic gates for quantum computing.
This information has been sourced, reviewed and adapted from materials provided by Graphenea.
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