IACM Colloquium
Speaker:
Giovanni Finocchio
University of Messina, Italy
Title:
Computing with spintronic devices and probabilistic bits
Abstract:
Spintronic technology, which takes advantage from the simultaneous use of charge and spin of the electron, has recently grown attention because of its success stories, starting from the hard disk read heads to the spin-transfer-torque MRAMs, in solid-state devices. A key building block of spintronic devices is the magnetic tunnel junction (MTJ). The undamental element of a MTJ is a tri-layer composed by two ferromagnets separated by a thin isolating material. The resistance of this tri-layer depends on the relative orientation of the magnetization vector of each ferromagnet. In general, one of the two is designed to be fixed while the other can be manipulated easily with field, current and/or voltage.
Together to the switching, it has been shown that in presence of a dc spin-polarized current it is possible to excited self-oscillation of the magnetization having the so called spin-transfer-torque oscillator while with an ac input it is achieved the diode effect. In this talk we will review the fundamental properties of spintronic devices and their applications as hardware building block in neuromorphic computing, in particular for the realization of neurons and synapses. Depending of the MTJ physical and geometrical parameters, it is possible to reproduce sigmoid and ReLU activation functions (most used so far at software level). we also show a possible use of spintronic diodes to implement analog multiplication, which is a key operation in convolutional neural networks (CNN), introducing the concept of degree of rectification (DOR). We will also discuss antiferromagnetic devicess for implementation of synapses and memristive systems for computing applications.
In the last part of the talk, I will review our recent results on Ising machines (IMs) and their potential hardware implementation with spintronic technology focusing on oscillator-based IMs and IMs built with p-bits (probabilistic computing). This computing paradigm is very promising to solve combinatorial optimization problems (COPs), which are a class of mathematical problems that have important applications in a variety of industrial and scientific fields, which span from logistics geoscience from water distribution network design o job scheduling. Many of these, such as maximum cut (Max-Cut), Boolean satisfiability (SAT) or the travelling salesman problem, are NP-complete or NP-hard, meaning in their worst-case instances they have no polynomial-time solution.
We show how the probabilistic computing can be used to solve max-sat instances (the other problems can be mapped on them) beating state-of-the art solvers having a time-to-solution to 95% at least one order of magnitude smaller.
Short Bio:
Giovanni Finocchio received the Ph.D. degree in advanced technologies in optoelectronic, photonic and micromagnetic modeling from the University of Messina, Italy, in 2006. Since 2010, he has been an Assistant Professor first and Associate professor now with the Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences at the University of Messina. He is director of the laboratory PETASPIN (Petascale computing and Spintronics) between University of Messina and Suzhou Institute of Nanotech and Nanobionics (China). His research interests include spintronics, skyrmions, and computing (https://scholar.google.co.uk/citations?user=eKDbn-oAAAAJ&hl=en). In the last 10 years, he served on many technical program committees of international conferences and organized more than 10 international conferences and workshops as Chair, Program Committee Member, or in other positions. He is regularly invited at conferences in Magnetism and Spintronics. He is also president o f Petaspin association (www.petaspin.com), chair of the IEEE Magnetics Italy chapter, AdCOM member of the IEEE Magnetics society and chair of the TC-16 on Quantum, neuromorphic and unconventional computing of the IEEE Nanotechnology council.
Time & Date:
15:00, Thursday, 30th of June, 2022
Zoom Info:
https://us06web.zoom.us/j/7761040361?pwd=dEs4TFZxck01Vk5PQWR1TUxKdndwUT09
Meeting ID: 776 104 0361
Passcode: 787479
Host:
Stavros Komineas
Speaker:
Giovanni Finocchio
University of Messina, Italy
Title:
Computing with spintronic devices and probabilistic bits
Abstract:
Spintronic technology, which takes advantage from the simultaneous use of charge and spin of the electron, has recently grown attention because of its success stories, starting from the hard disk read heads to the spin-transfer-torque MRAMs, in solid-state devices. A key building block of spintronic devices is the magnetic tunnel junction (MTJ). The undamental element of a MTJ is a tri-layer composed by two ferromagnets separated by a thin isolating material. The resistance of this tri-layer depends on the relative orientation of the magnetization vector of each ferromagnet. In general, one of the two is designed to be fixed while the other can be manipulated easily with field, current and/or voltage.
Together to the switching, it has been shown that in presence of a dc spin-polarized current it is possible to excited self-oscillation of the magnetization having the so called spin-transfer-torque oscillator while with an ac input it is achieved the diode effect. In this talk we will review the fundamental properties of spintronic devices and their applications as hardware building block in neuromorphic computing, in particular for the realization of neurons and synapses. Depending of the MTJ physical and geometrical parameters, it is possible to reproduce sigmoid and ReLU activation functions (most used so far at software level). we also show a possible use of spintronic diodes to implement analog multiplication, which is a key operation in convolutional neural networks (CNN), introducing the concept of degree of rectification (DOR). We will also discuss antiferromagnetic devicess for implementation of synapses and memristive systems for computing applications.
In the last part of the talk, I will review our recent results on Ising machines (IMs) and their potential hardware implementation with spintronic technology focusing on oscillator-based IMs and IMs built with p-bits (probabilistic computing). This computing paradigm is very promising to solve combinatorial optimization problems (COPs), which are a class of mathematical problems that have important applications in a variety of industrial and scientific fields, which span from logistics geoscience from water distribution network design o job scheduling. Many of these, such as maximum cut (Max-Cut), Boolean satisfiability (SAT) or the travelling salesman problem, are NP-complete or NP-hard, meaning in their worst-case instances they have no polynomial-time solution.
We show how the probabilistic computing can be used to solve max-sat instances (the other problems can be mapped on them) beating state-of-the art solvers having a time-to-solution to 95% at least one order of magnitude smaller.
Short Bio:
Giovanni Finocchio received the Ph.D. degree in advanced technologies in optoelectronic, photonic and micromagnetic modeling from the University of Messina, Italy, in 2006. Since 2010, he has been an Assistant Professor first and Associate professor now with the Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences at the University of Messina. He is director of the laboratory PETASPIN (Petascale computing and Spintronics) between University of Messina and Suzhou Institute of Nanotech and Nanobionics (China). His research interests include spintronics, skyrmions, and computing (https://scholar.google.co.uk/citations?user=eKDbn-oAAAAJ&hl=en). In the last 10 years, he served on many technical program committees of international conferences and organized more than 10 international conferences and workshops as Chair, Program Committee Member, or in other positions. He is regularly invited at conferences in Magnetism and Spintronics. He is also president o f Petaspin association (www.petaspin.com), chair of the IEEE Magnetics Italy chapter, AdCOM member of the IEEE Magnetics society and chair of the TC-16 on Quantum, neuromorphic and unconventional computing of the IEEE Nanotechnology council.
Time & Date:
15:00, Thursday, 30th of June, 2022
Zoom Info:
https://us06web.zoom.us/j/7761040361?pwd=dEs4TFZxck01Vk5PQWR1TUxKdndwUT09
Meeting ID: 776 104 0361
Passcode: 787479
Host:
Stavros Komineas