Abstract

Quantum spin Hall effect (QSHE) a fascinating topological phenomenon that could happen when electrons are confined in two-dimension (2D). It plays an important role in understanding fundamental topological physics principle in materials, as well as in engineering low-power electronic and quantum computation device applications.

In this project, we will attempt to realize QSHE in heterostructures formed by atomically thin 2D materials. We will employ electron transport measurements at cryogenic temperatures and search for the quantized conductance as evidence of QSHE. We will get theory support from Dr. Joaquín Fernández-Rossier at the International Iberian Nanotechnology Laboratory (INL), Portugal, to design experiments and understand the data obtained. In addition, the experimental group of Sascha Sadewasser will contribute with the growth of as a substrate materials using molecular beam epitax. We will arrange exchanges of staff and students to facilitate realizing the goal of this project.

Beginning with this seed project, we expect to establish a long-term collaboration to generate impacts in higher-education, fundamental physic research, and industrial application in MIT and in Portugal.

MIT PI
Long Ju, Assistant Professor, Department of Physics

PT PIs
Joaquín Fernández-Rossier, International Iberian Nanotechnology Laboratory, group leader of Theory of Quantum Nanostructures and tenured staff researcher, Portugal
Sascha Sadewasser, International Iberian Nanotechnology Laboratory, Leader of the Laboratory for Nanostructured Solar Cells

This grant is extended

Abstract

The advent of 2D crystalline materials has enabled the fabrication of novel devices with unique capabilities different from conventional 3D materials. Of particular interest are devices where the ability to control the stacking order and rotational alignment between 2D materials enables the engineering of novel tunable phases of matter. This proposal aims to investigate a new generation of nanoelectronic sensors based on novel 2D synthetic ferroelectric devices and twisted bilayer graphene devices. These sensors are expected to provide advantages such as ultra-fast switching speed, long endurance, biocompatibility, and compatibility with existing complementary metal-oxide-semiconductor technology. This work will involve a close collaboration between MIT and Portuguese researchers at the International Iberian Nanotechnology Institute (INL) paving the way to advanced technology applications of interest to the health sciences and pharmaceutical industry in Portugal.

MIT PI
Pablo Jarillo-Herrero, Professor, Department of Physics

PT PI
Dr. Pedro Alpuim, International Iberian Nanotechnology Institute, Research Group Leader.
Dr. Joaquin Fernandez-Rossier, International Iberian Nanotechnology Institute, Research Group Leader

This grant is renewed until August 31, 2027

Abstract

We aim to develop neuromorphic computing systems by exploiting the stochastic nature of nanoscale spintronic devices. Currently neural networks have achieved remarkable success in various application areas. However, existing silicon-based hardware exhibits inefficiency at processing compute-intensive models compared to the human brain. Bio-inspired computing models based on stochastic activations and learning rules provide new opportunities for developing efficient neuromorphic systems with complex cognitive capabilities. In this proposal, we will leverage the intrinsic stochasticity from the compact and energy-efficient spintronic devices for realizing stochastic neuro-mimetic components, and realize algorithms and architecture to achieve balanced performance among accuracy, robustness, synaptic memory requirements, and energy efficiency. Particularly, we will develop stochastic spin-orbit torque magnetic tunnel junctions for both neurons and synapses. Compared to state of the art, the proposed devices and circuits will minimize the influence of noises and device variations, leading to a scalable solution for robust and efficient implementation of stochastic neural networks.

MIT PI
Luqiao Liu, Associate Professor, Department of Electrical Engineering and Computer Science

PT PI
Susana Cardoso de Freitas, INESC-MN and Instituto Superior Tecnico, Principal Investigator and Full Professor