More Like this

1. Lateral inhibition in magnetic domain wall racetrack arrays for neuromorphic computing

   https://doi.org/10.1117/12.2568870  

   Cui, Can; Akinola, Otitoaleke G.; Hassan, Naimul; Bennett, Christopher H.; Marinella, Matthew J.; Friedman, Joseph S.; Incorvia, Jean Anne (August 2020, Proc. SPIE, Spintronics XIII)

   Drouhin, Henri-Jean M.; Wegrowe, Jean-Eric; Razeghi, Manijeh (Ed.)

   Neuromorphic computing captures the quintessential neural behaviors of the brain and is a promising candidate for the beyond-von Neumann computer architectures, featuring low power consumption and high parallelism. The neuronal lateral inhibition feature, closely associated with the biological receptive eld, is crucial to neuronal competition in the nervous system as well as its neuromorphic hardware counterpart. The domain wall - magnetic tunnel junction (DW-MTJ) neuron is an emerging spintronic arti cial neuron device exhibiting intrinsic lateral inhibition. This work discusses lateral inhibition mechanism of the DW-MTJ neuron and shows by micromagnetic simulation that lateral inhibition is eciently enhanced by the Dzyaloshinskii-Moriya interaction (DMI). 

   more » « less
2. Intrinsic Lateral Inhibition Facilitates Winner-Take-All in Domain Wall Racetrack Arrays for Neuromorphic Computing

   https://doi.org/10.1109/ISCAS48785.2022.9937784  

   Cui, Can; Akinola, Otitoaleke G.; Hassan, Naimul; Bennett, Christopher H.; Marinella, Matthew J.; Friedman, Joseph S.; Incorvia, Jean Anne (May 2022, 2022 IEEE International Symposium on Circuits and Systems (ISCAS))

   Neuromorphic computing is a promising candidate for beyond-von Neumann computer architectures, featuring low power consumption and high parallelism. Lateral inhibition and winner-take-all (WTA) features play a crucial role in neuronal competition of the nervous system as well as neuromorphic hardwares. The domain wall - magnetic tunnel junction (DWMTJ) neuron is an emerging spintronic artificial neuron device exhibiting intrinsic lateral inhibition. In this paper we show that lateral inhibition parameters modulate the neuron firing statistics in a DW-MTJ neuron array, thus emulating soft-winner-take-all (WTA) and firing group selection. 

   more » « less
3. Three Artificial Spintronic Leaky Integrate-and-Fire Neurons

   https://doi.org/10.1142/S2010324720400032  

   Brigner, Wesley H.; Hu, Xuan; Hassan, Naimul; Jiang-Wei, Lucian; Bennett, Christopher H.; Garcia-Sanchez, Felipe; Akinola, Otitoaleke; Pasquale, Massimo; Marinella, Matthew J.; Incorvia, Jean Anne; et al (January 2020, SPIN)

   Due to their non-volatility and intrinsic current integration capabilities, spintronic devices that rely on domain wall (DW) motion through a free ferromagnetic track have garnered significant interest in the field of neuromorphic computing. Although a number of such devices have already been proposed, they require the use of external circuitry to implement several important neuronal behaviors. As such, they are likely to result in either a decrease in energy efficiency, an increase in fabrication complexity, or even both. To resolve this issue, we have proposed three individual neurons that are capable of performing these functionalities without the use of any external circuitry. To implement leaking, the first neuron uses a dipolar coupling field, the second uses an anisotropy gradient, and the third uses shape variations of the DW track. 

   more » « less
4. A perspective on electrical generation of spin current for magnetic random access memories

   https://doi.org/10.1063/5.0084551  

   Safranski, Christopher; Sun, Jonathan_Z; Kent, Andrew_D (April 2022, Applied Physics Letters)

   Spin currents are used to write information in magnetic random access memory (MRAM) devices by switching the magnetization direction of one of the ferromagnetic electrodes of a magnetic tunnel junction (MTJ) nanopillar. Different physical mechanisms of conversion of charge current to spin current can be used in two-terminal and three-terminal device geometries. In two-terminal devices, charge-to-spin conversion occurs by spin filtering in the MTJ's ferromagnetic electrodes and present day MRAM devices operate near the theoretically expected maximum charge-to-spin conversion efficiency. In three-terminal devices, spin–orbit interactions in a channel material can also be used to generate large spin currents. In this Perspective article, we discuss charge-to-spin conversion processes that can satisfy the requirements of MRAM technology. We emphasize the need to develop channel materials with larger charge-to-spin conversion efficiency—that can equal or exceed that produced by spin filtering—and spin currents with a spin polarization component perpendicular to the channel interface. This would enable high-performance devices based on sub-20 nm diameter perpendicularly magnetized MTJ nanopillars without need of a symmetry breaking field. We also discuss MRAM characteristics essential for CMOS integration. Finally, we identify critical research needs for charge-to-spin conversion measurements and metrics that can be used to optimize device channel materials and interface properties prior to full MTJ nanopillar device fabrication and characterization. 

   more » « less
5. Complementary congruent and opposite neurons achieve concurrent multisensory integration and segregation

   https://doi.org/10.7554/eLife.43753  

   Zhang, Wen-Hao; Wang, He; Chen, Aihua; Gu, Yong; Lee, Tai Sing; Wong, KY Michael; Wu, Si (May 2019, eLife)

   Our brain perceives the world by exploiting multisensory cues to extract information about various aspects of external stimuli. The sensory cues from the same stimulus should be integrated to improve perception, and otherwise segregated to distinguish different stimuli. In reality, however, the brain faces the challenge of recognizing stimuli without knowing in advance the sources of sensory cues. To address this challenge, we propose that the brain conducts integration and segregation concurrently with complementary neurons. Studying the inference of heading-direction via visual and vestibular cues, we develop a network model with two reciprocally connected modules modeling interacting visual-vestibular areas. In each module, there are two groups of neurons whose tunings under each sensory cue are either congruent or opposite. We show that congruent neurons implement integration, while opposite neurons compute cue disparity information for segregation, and the interplay between two groups of neurons achieves efficient multisensory information processing. 

   more » « less