Increasing Flips per Second and Speed of p-Computers by Using Dilute
Magnetic Semiconductors to Implement Binary Stochastic Neurons
Abstract
Probabilistic computing with binary stochastic neurons (BSN) implemented
with low- or zero-energy barrier nanoscale ferromagnets (LBMs)
possessing in-plane magnetic anisotropy has emerged as an efficient
paradigm for solving computationally hard problems. The fluctuating
magnetization of an LBM at room temperature encodes a p-bit which is the
building block of a BSN. Its only drawback is that the dynamics of
common (transition metal) ferromagnets are relatively slow and hence the
number of uncorrelated p-bits that can be generated per second – the
so-called “flips per second” (fps) – is insufficient, leading
to slow computational speed in autonomous co-processing with
p-computers. Here, we show that a simple way to increase fps is
to replace commonly used ferromagnets (e.g. Co, Fe, Ni), which have
large saturation magnetization Ms, with a dilute magnetic
semiconductor like GaMnAs with much smaller saturation magnetization.
The smaller Ms reduces the energy barrier within the LBM and
increases the fps significantly. It also offers other benefits
such as increased packing density for increased parallelization and
reduced device to device variation. This provides a way to realize the
hardware acceleration and energy efficiency promise of p-computers.