Researchers Widen Spin Energy Gap in 2D Quantum Well

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Researchers from University of New South Wales tripled the energy gap between the two spin states of holes in a 2D quantum well

Electronic devices consume high amount of energy, however, lower-powered devices that use a particle’s spin to move information around in a circuit can lead to devices with low energy consumption. Now a research led by Elizabeth Marcellina of the University of New South Wales in Australia, demonstrated a novel all-electric method to manipulate the spin of holes in a quantum-well device. Although, magnetic fields is generally used to control electron spins, significant amount of energy is required for the process and they are hard to localize that makes them impractical for manipulating spins in nanoscale devices. Moreover, the energy difference between the two states of a spin cannot be easily adjusted with magnetic fields. Such drawbacks prove magnetic-field-controlled devices slow for applications.

The device developed by the team changes an electric field instead of a magnetic field, to control the spins of holes in a quantum well. The electric field changes the speed of the holes and allows to manipulate the spin energy difference. A larger electric field leads to faster moving holes that increases the energy difference between the spin states due to spin-orbit coupling in the quantum well. The team adjusted the electric field to achieve a threefold increase in the energy difference between the holes’ spin up and spin down states. Although, this increase in energy allows faster flipping of spins, the team urged that further research is required to determine the achievable speed gain. The research was published in the journal Physical Review Letters on August 15, 2018.

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