ICMAB Seminar

IN PERSON EVENT

By Tamalika Banerjee, University of Groningen, the Netherlands

Abstract:

Spintronics has opened many avenues in condensed matter, revolutionized the data storage industry and holds rich prospects for unconventional computing approaches. Conventional computing is based on the von Neumann architecture which is limited by a memory bottleneck, high power consumption and heat dissipation. This is primarily due to the non-colocation of memory and processing units, making the hardware sequential and deterministic. These challenges can be efficiently tackled by processing the information on the signal, similar to what the human brain does. This has spurred the development of alternative, domain-specific computing paradigms beyond the conventional von-Neumann architecture using analogue devices, known as memristors, that  collocate memory and processing in the same functional unit. The material class of complex oxides, where the fundamental thrust is on understanding the strong correlations between the electron charge, spin and  orbital degrees of freedom has established itself as an important material system for designing memristors.

In this seminar, I will discuss two broad examples on how the rich phase space, intrinsic to complex oxides, can be exploited in thin films and in their heterointerfaces for this purpose. In the first example an all-oxide magnetic tunnel junction (MTJ) of SrRuO3 (SRO)/SrTiO3 (STO)/SRO, exhibiting a strong  perpendicular magnetic anisotropy will be discussed. MTJs utilizing electrodes with perpendicular magnetic anisotropy are of great interest for future nonvolatile memory and logic chips. This stack shows a large TMR, which cannot be explained using the conventional tunneling spin polarization principles but needs to incorporate the symmetry mismatch between the propagating Bloch states of the minority and majority spin bands of SRO (001). Interestingly this MTJ exhibits atleast three stable resistance states, opening pathways for unconventional computing approaches.

In the second example, we show how an entire network of strained films of La0.67Sr0.33MnO3  demonstrates complex biologically plausible brain functionalities such as self-oscillation and integrate and fire neurons. This arises due to a combination of an intrinsic coupled phase transition in La0.67Sr0.33MnO3 and octahedral distortion due to the textured surface of the LAlO3 substrate leading to multiple negative differential resistance (NDR) regimes in the network, at room temperature. This leads to the demonstration of voltage-tunable oscillators, dynamically oscillating at variable frequencies (kHz to MHz). I will also discuss how the time dynamics of the integrate, and fire neuron network leads to the development of probabilistic bits, useful for ultra-low power stochastic hardware.

Short Bio:

Tamalika Banerjee is a Rosalind Franklin Fellow, Professor & Chair of Spintronics of Functional Materials group at the Zernike Institute for Advanced Materials, University of Groningen, and member of CogniGron Centre. Her research group primarily works on Oxide Spintronics and their devices for brain-inspired computing. She is also the Founder (2024) of IMChip, whose patented technology is used for neuromorphic computing hardware for sustainable and responsible AI applications.

She is also a Visiting Faculty at CeNSE, Indian Institute of Science, Bangalore, India (2026- ).

She also held a Scientific Associate Investigator position at FLEET, ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Australia (till 2024)

She obtained her PhD from the University of Madras, India, followed by post doctoral stays at the Francis Bitter Magnet Laboratory, MIT, USA, Tata Institute of Fundamental Research, Mumbai, India, and MESA⁺ Institute for Nanotechnology at the University of Twente, the Netherlands. She is a Senior member of IEEE.

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