Northwestern University

Jul
11
Wed 2:00 PM

EECS Seminar Speaker: Prof. Giovanni Finocchio, Assistant Professor of Electrical Engineering at University of Messina, "Fundamentals of Spintronic Energy Harvesting & Skyrmionic Devices"

Prof. Giovanni Finocchio

When: Wednesday, July 11, 2018
2:00 PM - 3:00 PM  

Where: Technological Institute, Room L440, 2145 Sheridan Road, Evanston, IL 60208 map it

Audience: Faculty/Staff - Student - Public - Post Docs/Docs - Graduate Students

Contact: Lana Kiperman  

Group: Electrical Engineering & Computer Science

Category: Lectures & Meetings

Description:

The EECS Department welcomes Prof. Giovanni Finocchio, Assistant Professor of Electrical Engineering at University of Messina.

Finocchio will present a talk entitled "Fundamentals of Spintronic Energy Harvesting & Skyrmionic Devices" on Wednesday, July 11 at 2pm in Tech Room L440.

Abstract: In this talk, I will discuss recent results in the field of spintronic energy harvesting and magnetic skyrmions, which we achieved in Messina in collaboration with experimental partners. Electromagnetic energy harvesting technologies offer an attractive energy source for applications in self-powered portable electronics in the “internet of things” (IoT) era. Here we show the development of a bias-field-free nanoscale spintronic diode (NSD) based on a magnetic tunnel junction (MTJ) having a canted magnetization in the free layer, and demonstrate that this NSD could be an efficient harvester of broadband ambient RF radiation, capable to efficiently harvest microwave powers of microWatt and below. We have measured the rectified voltage with an RF current in the absence of an applied magnetic field, by applying an RF current to the device through a bias tee using a signal generator, while the rectification voltage VDC across the MTJ is recorded with a nano-voltmeter. The frequency response of the NSD shows that a novel type of frequency behaviour, i.e. broadband response, is achieved. As an example, we show that with a RF input power of PRF = 10 μW, the NSD rectifies a nearly constant voltage across a 100 to 550 MHz range.

Magnetic skyrmions are topological protected solitons with a chirality that can be stabilized by the Dzyaloshinskii-Moriya interaction (DMI). Understanding the physical properties of magnetic skyrmions is important for fundamental research with the aim to develop new spintronic device paradigms, where both logic and memory can be integrated at the same level or for unconventional computing. We have recently studied different mechanisms of stabilization of skyrmions in confined devices: One of them needs a large DMI to introduce an energetic minimum in the energy landscape, associated with a metastable skyrmion state, and another mechanism that provides a skyrmion state where the size depends on a trade off among magnetostatic, exchange and DMI energies. In this seminar, we will show a universal model based on the micromagnetic formalism combining a proper ansatz and scaling relationships, and a specific Q-d phase space (quality factor Q vs. reduced DMI d), that can be used to study skyrmion stability as a function of magnetic field and temperature.

Bio: Prof. Giovanni Finocchio received the Ph.D. degree in advanced technologies in optoelectronic, photonic and micromagnetic modeling from the University of Messina, Italy, in 2006. From 2006 to 2010, he was a Research Assistant with the University of Messina. Since 2010, he has been an Assistant Professor with the Department of Mathematical and Computer Sciences, Physical Sciences and Earth Sciences, University of Messina. He is the author of books, patents, and over 140 articles published in well established journals. His research interests include the modeling of materials for spintronic applications, theoretical and applied spintronics, magnetic skyrmions, nanomagnetism, parallel computations, the signal processing of non-stationary signals, the biomedical applications of magnetoresistive devices, and metamaterials for seismic applications. He is founder of two start-up companies. 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.

Hosted by EECS Prof. Pedram Khalili

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