2025-05-19 アルゴンヌ国立研究所（ANL）
A transmission electron microscope image of a nanomagnetic Galton board. A domain wall is injected at the top of the board and makes a decision to go down the left or right path at each y-shaped intersection. (Image by Hanu Arava/Argonne National Laboratory.)
＜関連情報＞
- https://www.anl.gov/article/understanding-randomness-argonne-researchers-visualize-decisionmaking-in-nanomagnetic-structures
- https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.134.086704
ナノマグネティック・ガルトン・ボードにおけるフィールド駆動型意思決定の実空間イメージング Real Space Imaging of Field-Driven Decision-Making in Nanomagnetic Galton Boards
H. Arava, D. Sanz-Hernandez, J. Grollier, and A. K. Petford-Long
Physical Review Letters Published: 26 February, 2025
DOI: https://doi.org/10.1103/PhysRevLett.134.086704
Abstract
A possible spintronic route to hardware implementation for decision-making involves injecting a domain wall into a bifurcated magnetic nanostrip resembling a Y-shaped junction. A decision is made when the domain wall chooses a particular path through the bifurcation. Recently, it was shown that a structure like a nanomagnetic Galton board, which is essentially an array of interconnected Y-shaped junctions, produces outcomes that are stochastic and therefore relevant to artificial neural networks. However, the exact mechanism leading to the robust nature of randomness is unknown. Here, we directly image the decision-making process in nanomagnetic Galton boards using Lorentz transmission electron microscopy. We identify that the stochasticity in nanomagnetic Galton boards arises as a culmination of (1) the topology of the injected domain wall, (2) dissimilarly sized vertices, and (3) the strength of the applied field. Our results pave the way to a detailed understanding of stochasticity in nanomagnetic networks.
