New spin logic device constructed using asymmetric quantum wells
New spin logic device constructed using asymmetric quantum wells lead image
Spintronic devices, those that utilize the spin of electrons to transmit, process, and store information, are widely developed for memory and logic applications. Recently there has been interest in applying spintronics to transistors and other switching devices, which could allow them to function with greater speed and energy efficiency than conventional CMOS devices.
Lee et al. use two asymmetric quantum wells to create a new reconfigurable spin logic device. At the bottom of the wells are ferromagnetic electrodes whose magnetization orientation controls the logic operation. The ferromagnetic terminals read the electrochemical potentials of the quantum wells and output a voltage corresponding to the difference between them.
The new system was tested at room temperature on four logic functions obtained by the switching of the electrodes’ magnetization direction. (The authors note the logic functions can also be obtained via spin transfer torque.) According to their test results, the quantum wells exhibit strong Rashba spin splitting, which helps circumvent the inefficient spin injection process. Additionally, signals detected from the Rashba channel were found to be two orders of magnitude greater than the spin injection signal from the ferromagnetic source, showing the system’s functionality at room temperature. However, the logic signal slowly decreases with increasing temperature, due to the temperature dependence of Rashba spin splitting.
Since the new technique doesn’t depend on gate capacitance, as with spin injection devices, the authors argue that it can operate much faster. The authors also claim that their device can be constructed much easier than current CMOS devices, since it contains fewer components.
Source: “Reconfigurable spin logic device using electrochemical potentials,” by Joo-hyeon Lee, Seokmin Hong, Hyung-jun Kim, Joonyeon Chang, and Hyun Cheo Koo, Applied Physics Letters (2019). The article can be accessed at https://doi.org/10.1063/1.5089274 .
