Ultra-fast artificial neuron: generation of picosecond-duration spikes in a current-driven antiferromagnetic auto-oscillator

Abstract

We demonstrate analytically and numerically, that a thin film of an antiferromagnetic (AFM) material, having biaxial magnetic anisotropy and being driven by an external spin-transfer torque signal, can be used for the generation of ultra-short “Dirac-delta-like” spikes. The duration of the generated spikes is several picoseconds for typical AFM materials and is determined by the inplane magnetic anisotropy and the effective damping of the AFM material. The generated output signal can consist of a single spike or a discrete group of spikes (“bursting”), which depends on the repetition (clock) rate, amplitude, and shape of the external control signal. The spike generation occurs only when the amplitude of the control signal exceeds a certain threshold, similar to the action of a biological neuron in response to an external stimulus. The “threshold” behavior of the proposed AFM spike generator makes possible its application not only in the traditional microwave signal processing but also in the future neuromorphic signal processing circuits working at clock frequencies of tens of gigahertz.

Electric‐Field‐Controlled Antiferromagnetic Spintronic Devices

“…The spikes of d) the anterior and e) the posterior neurons in a neural network. Reproduced with permission 133. Copyright 2018, Springer Nature.…”

Terahertz frequency spectrum analysis with a nanoscale antiferromagnetic tunnel junction

“…This bandwidth has been dubbed the "THz gap" because traditional silicon electronics and traditional photonics hardware do not function effectively and thus are not capable of generating, detecting, or otherwise processing these signals [1][2][3][4] . In contrast, antiferromagnetic (AFM) materials show intrinsic resonant characteristics within the THz gap, and have been identified as building blocks for a new class of devices that will function at THz frequencies, as shown in many recent experimental and theoretical works [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] . Thus far, there have been proposals for miniaturized THz frequency (TF) detectors 16,17 , sources [18][19][20] , and spiking neurons for neuromorphic applications 21,22 .…”

Synchronization of an Antiferromagnetic Josephson-like Oscillator with an External AC Signal

“…However, these spintronic devices have at least one critical drawback: they can usually operate at frequencies less than ~ 50 GHz. In contrast to this, antiferromagnets (AFMs) possessing a very strong internal magnetic field of the exchange origin have characteristic working frequencies of several hundreds of GHz and even several THz [12][13][14][15][16][17][18]. Hence, antiferromagnetic materials can be useful for the development and creation of current-driven ultrafast nanoscale [12][13][14][15] and microscale [16,17] devices operating in the frequency range of 0.1-10 THz.…”