Short-Term Plasticity and Long-Term Potentiation in Magnetic Tunnel Junctions: Towards Volatile Synapses

Synaptic memory is considered to be the main element responsible for learning and cognition in humans. Although traditionally non-volatile long-term plasticity changes have been implemented in nanoelectronic synapses for neuromorphic applications, recent studies in neuroscience have revealed that biological synapses undergo meta-stable volatile strengthening followed by a long-term strengthening provided that the frequency of the input stimulus is sufficiently high. Such "memory strengthening" and "memory decay" functionalities can potentially lead to adaptive neuromorphic architectures. In this paper, we demonstrate the close resemblance of the magnetization dynamics of a Magnetic Tunnel Junction (MTJ) to short-term plasticity and long-term potentiation observed in biological synapses. We illustrate that, in addition to the magnitude and duration of the input stimulus, frequency of the stimulus plays a critical role in determining long-term potentiation of the MTJ. Such MTJ synaptic memory arrays can be utilized to create compact, ultra-fast and low power intelligent neural systems.

[1]  W. Marsden.  I and J , 2012 .

[2]  Wei Yang Lu,et al.  Nanoscale memristor device as synapse in neuromorphic systems. , 2010, Nano letters.

[3]  Willis F. Overton,et al.  Advances in research and theory , 1977 .

[4]  W. Regehr,et al.  Short-term synaptic plasticity. , 2002, Annual review of physiology.

[5]  Slonczewski.  Conductance and exchange coupling of two ferromagnets separated by a tunneling barrier. , 1989, Physical review. B, Condensed matter.

[6]  Li Sun,et al.  Tuning the properties of magnetic nanowires , 2006, IBM J. Res. Dev..

[7]  J R Morante,et al.  Introducing Professor J R Morante as Editor in Chief of Journal of Physics D: Applied Physics , 2017 .

[8]  K L Magleby,et al.  The effect of repetitive stimulation on facilitation of transmitter release at the frog neuromuscular junction , 1973, The Journal of physiology.

[9]  Physics Letters , 1962, Nature.

[10]  Etienne,et al.  Giant magnetoresistance of (001)Fe/(001)Cr magnetic superlattices. , 1988, Physical review letters.

[11]  J. Gilman,et al.  Nanotechnology , 2001 .

[12]  Binasch,et al.  Enhanced magnetoresistance in layered magnetic structures with antiferromagnetic interlayer exchange. , 1989, Physical review. B, Condensed matter.

[13]  David Renshaw,et al.  Custom Integrated Circuits Conference (CICC) , 1990 .

[14]  Kaushik Roy,et al.  Spin-Orbit Torque Induced Spike-Timing Dependent Plasticity , 2014, ArXiv.

[15]  Steven M. Nowick,et al.  ACM Journal on Emerging Technologies in Computing Systems , 2010, TODE.

[16]  S. J. Martin,et al.  Synaptic plasticity and memory: an evaluation of the hypothesis. , 2000, Annual review of neuroscience.

[17]  Matthew J. Rosseinsky,et al.  Physical Review B , 2011 .

[18]  Joseph E LeDoux,et al.  Structural plasticity and memory , 2004, Nature Reviews Neuroscience.

[19]  Steve B. Furber,et al.  Modeling Spiking Neural Networks on SpiNNaker , 2010, Computing in Science & Engineering.

[20]  W. Cowan,et al.  Annual Review of Neuroscience , 1995 .

[21]  M. De Graef,et al.  Demagnetization factors for elliptic cylinders , 2005 .

[22]  G. Bi,et al.  Synaptic modification by correlated activity: Hebb's postulate revisited. , 2001, Annual review of neuroscience.

[23]  G. Bower,et al.  THE PSYCHOLOGY OF LEARNING AND M·OTIVATION , 2001 .

[24]  D. Signorini,et al.  Neural networks , 1995, The Lancet.

[25]  T. Hasegawa,et al.  Short-term plasticity and long-term potentiation mimicked in single inorganic synapses. , 2011, Nature materials.

[26]  A. J. Freeman,et al.  Journal of Magnetism and Magnetic Materials. Volumes 198-199, 1 June 1999, , 1999 .

[27]  O. A. Trowell.  Annual Review of Physiology , 1948, Nature.

[28]  Masakazu Aono,et al.  Synaptic plasticity and memory functions achieved in a WO3−x-based nanoionics device by using the principle of atomic switch operation , 2013, Nanotechnology.

[29]  Wei Lu,et al.  Short-term Memory to Long-term Memory Transition in a Nanoscale Memristor , 2022 .

[30]  Werner Scholz,et al.  Micromagnetic simulation of thermally activated switching in fine particles , 2001 .

[31]  Geoffrey W. Burr,et al.  Nanoscale electronic synapses using phase change devices , 2013, JETC.

[32]  D. Fayuk,et al.  The Journal of Physiology , 1978, Medical History.

[33]  D. Ralph,et al.  Spin transfer torque devices utilizing the giant spin Hall effect of tungsten , 2012, 1208.1711.

[34]  M. Julliere.  Tunneling between ferromagnetic films , 1975 .