< Previous18 ARC CENTRE OF EXCELLENCE IN FUTURE LOW-ENERGY ELECTRONICS TECHNOLOGIES PARTNER INVESTIGATORS Allan MacDonald University of Texas Antonio Castro Neto National University of Singapore Grzegorz Sek Wroclaw University of Science and Technology Ferenc Krausz Max Planck Institute of Quantum Optics Anton Tadich Australian Synchrotron David Neilson University of Camerino Andrea Perali University of Camerino Barbaros Oezyilmaz National University of Singapore Gil Refael California Institute of Technology James Hone Columbia University Sven Hoefling University of Wurzburg Hai-Qing Lin Beijing Computational Science Research Center Qi-Kun Xue Tsinghua University William Phillips University of Maryland Pu Yu Tsinghua University Jairo Sinova Mainz University Shuyun Zhou Tsinghua University Johnpierre Paglione University of Maryland Ian Spielman University of Maryland LEGEND Research theme 1, topological materials Research theme 2, exciton superfluids Research theme 3, light-transformed materials Enabling technology A, atomically-thin materials Enabling technology B, nano-device fabrication Victor Gurarie University of Colorado Victor Galitski University of Maryland FLEET TEAM19 FLEET 2018 ANNUAL REPORT SCIENTIFIC ASSOCIATE INVESTIGATORS Bent Weber Nanyang Technological University Singapore Jian-zhen Ou RMIT University Mark Edmonds Monash University Paul Dyke Swinburne University Jesper Levinsen Monash University Joanne Etheridge Monash University Nicholas Karpowicz Max Planck Institute of Quantum Optics Torben Daeneke RMIT University David Cortie University of Wollongong Martin Schultze Max Planck Institute of Quantum Optics Shaffique Adam National University of Singapore Bernard Field Monash University Yuerui (Larry) Lu Australian National University Zhi Li University of Wollongong Qile Li Monash University Mitchell Conway Swinburne University Matthew Hendy Monash University Zhanning Wang University of New South Wales Yik Kheng Lee RMIT University Zeb Krix University of New South Wales Matthew Gebert Monash University Oliver Stockdale University of Queensland MASTERS AND HONOURS STUDENTS Zixin Liang MASTERS STUDENT Australian National University20 ARC CENTRE OF EXCELLENCE IN FUTURE LOW-ENERGY ELECTRONICS TECHNOLOGIES RESEARCH FELLOWS Ali Zavabeti RMIT University Cornelius Krull Monash University Babar Shabbir Monash University Changxi Zheng Monash University Aydin Keser University of New South Wales Benjamin Carey Alumnus, now at University of Munster Carlos Claiton Noschang Kuhn Swinburne University Daisy Qingwen Wang University of New South Wales Dmitry Miserev Alumnus, now at University of Basel Feixiang Xiang University of New South Wales Gary Beane Monash University Elizabeth Marcellina Alumnus, now at Nanyang Technological University Singapore David Colas University of Queensland Eliezer Estrecho Australian National University Daniel Sando University of New South Wales Golrokh Akhgar RMIT University Harley Scammell Alumnus, now at Harvard University Guolin Zheng RMIT University LEGEND Research theme 1, topological materials Research theme 2, exciton superfluids Research theme 3, light-transformed materials Enabling technology A, atomically-thin materials Enabling technology B, nano-device fabrication Guangyao Li Monash University FLEET TEAM21 FLEET 2018 ANNUAL REPORT Isabela Alves de Castro Alumnus, now at Alcoa Karina Hudson University of New South Wales Matt Reeves University of Queensland Jackson Smith RMIT University Maciej Pieczarka Australian National University Pankaj Sharma University of New South Wales Pankaj Bhalla Beijing Computational Science Research Center Stuart Earl Swinburne University Ivan Herrera Swinburne University Kun Qi Monash University Matthew Rendell University of New South Wales Sascha Hoinka Swinburne University Paul Atkin RMIT University Steven Barrow Alumnus, RMIT University Shivananju Bannur Nanjunda Monash University Yun Suk Eo University of Maryland Yupeng Zhang Alumnus, now at Shenzhen University Shilpa Sanwlani Swinburne University Samuel Bladwell University of New South Wales Shaun Johnstone Monash University Peggy Qi Zhang University of New South Wales Weizhe Liu Monash University Zengji Yue University of Wollongong Ziyu Wang University of New South Wales Zhigao Dai Monash University Yuefeng Yin Monash University22 ARC CENTRE OF EXCELLENCE IN FUTURE LOW-ENERGY ELECTRONICS TECHNOLOGIES PHD STUDENTS Chang Liu Monash University Hanqing Yin Monash University Chutian Wang Monash University Fei Hou University of New South Wales Cheng Tan RMIT University Dhaneesh Gopalakrishnan Monash University Fan Ji University of New South Wales Haoran Mu Monash University Jackson Wong University of New South Wales Jesse Vaitkus RMIT University Jiali Zeng University of New South Wales Jialu Zheng Monash University Hong Liu University of New South Wales James Collins Monash University Hareem Khan RMIT University Lawrence Farrar RMIT University Matthias Wurdack Australian National University Maryam Boozarjmehr Australian National University LEGEND Research theme 1, topological materials Research theme 2, exciton superfluids Research theme 3, light-transformed materials Enabling technology A, atomically-thin materials Enabling technology B, nano-device fabrication Marina Castelli Monash University FLEET TEAM23 FLEET 2018 ANNUAL REPORT Nuriyah Aloufi RMIT University Oliver Sandberg University of Queensland Oliver Paull University of New South Wales Pavel Kolesnichenko Swinburne University I enjoy this field of research because there is so much that needs to be explored experimentally. It is a relatively new field, with a lot of unanswered questions. Wafa Afzal FLEET PhD student Tyson Peppler Swinburne University Zhichen Wan Monash University Weiyao Zhao University of Wollongong Vivasha Govinden University of New South Wales Yonatan Ashlea Alava University of New South Wales Wenzhi Yu Monash University Yun Li Monash University Zhi-Tao Deng University of Queensland Wafa Afzal University of Wollongong Qingdong Ou Monash University Rebecca Orrell-Trigg University of New South Wales Tatek Lemma Swinburne University Sultan Albarakati RMIT University Tinghe Yun Monash University Tommy Bartolo RMIT University Samuel Wilkinson RMIT University Stuart Burns University of New South Wales24 RESEARCH THEME 1 ARC CENTRE OF EXCELLENCE IN FUTURE LOW-ENERGY ELECTRONICS TECHNOLOGIES PROF ALEX HAMILTON Leader, Research theme 1 UNSW “FLEET enables our researchers to tackle big challenges by working with scientists all over Australia” Expertise: electronic conduction in two- dimensional (2D) and nanoscale transistors, spin-orbit interactions, behaviour of holes in semiconductor nanostructures Research outputs: 210+ papers, 3700+ citations, h-index 30 RESEARCH THEME 1: TOPOLOGICAL MATERIALS FLEET’s first research theme seeks to achieve electrical current flow with near-zero resistance based on a paradigm shift in the understanding of condensed-matter physics and materials science: the advent of topological insulators. Unlike conventional insulators, which do not conduct electricity at all, topological insulators conduct electricity, but only along their edges. Along those edge paths, they conduct electrons strictly in one direction, without the ‘back-scattering’ of electrons that dissipates energy in conventional electronics. FLEET’s challenge is to create topological materials that will operate as insulators in their interior, and have switchable conduction paths along their edges. For the new technology to become a viable alternative to traditional transistors, the desired properties must be achievable at room temperature – there’s no point in saving energy on transistor switching if you have to use even more energy to keep the system supercold. Topological transistors would ‘switch’, just as a traditional transistor does. Applying a controlling voltage would switch the edge paths of the topological material between being a topological insulator (‘on’) and a conventional insulator (‘off’). Approaches used are: • Magnetic topological insulators and quantum anomalous Hall effect (QAHE) • Topological Dirac semimetals • Artificial topological systems. IN 2019, FLEET WILL: • Develop techniques to electrically probe topological crystals grown in high-vacuum chambers • Develop new theoretical techniques and models to understand and predict the electronic properties of topological materials • Fabricate artificial crystals out of conventional semiconductors. PhD student Vivasha Govinden (UNSW) studies ferroelectric coupling, seeking an enhanced electromechanical response that could be used in future nanoelectronic sensors and electronics.25 FLEET 2018 ANNUAL REPORT 2018 HIGHLIGHTS • First demonstration of electrical switching of a material from a normal to a topological insulator, using an electric field, a key step towards making a topological transistor (see case study, p26) • New, fundamental theoretical work to understand the spin-orbit interaction that is behind topological DEFINITIONS artificial topological systems Artificial analogues of graphene and 2D topological insulators bandgap The energy gap that defines whether a material is a conductor, insulator or semiconductor; a large bandgap is required for a material to still be topological at room temperature dissipationless current Electric current that flows without wasted dissipation of energy quantum anomalous Hall effect (QAHE) A magnetic effect giving a material conducting edges carrying current in one direction only, completely without resistance spin-orbit coupling The interaction between electrons’ movement and their inherent angular momentum, which drives topological effects DID YOU KNOW... Information and communication technology (ICT) now contribute as much to climate change as the aviation industry. materials, showing that spin-orbit interactions can significantly alter the Hall effect • Development of a new photodetector based on the topological crystalline insulator SnTe • Proposal for new superconducting device for routing electronic signals used in quantum circuits. FLEET Research Fellow Matthew Rendell and undergrad student Olivia Kong (UNSW). 26 ARC CENTRE OF EXCELLENCE IN FUTURE LOW-ENERGY ELECTRONICS TECHNOLOGIES This new switch works on a fundamentally different principle than the transistors in today’s computers. We envision such switches facilitating a completely new computing technology, which uses lower energy. Dr Mark Edmonds FLEET Scientific AI, Monash University CASE STUDY SWITCHING TOPOLOGICAL STATE OFF AND ON: STEP TOWARDS A TOPOLOGICAL TRANSISTOR FLEET researchers achieve world first: successfully ‘switching’ a topological material, via application of an electric field. This success represents the first step in creating a functioning topological transistor – a key goal of FLEET’s Research theme 1. “In a topological insulator’s edge paths, electrons can only travel in one direction,” explains lead author Dr Mark Edmonds. “And this means there can be no ‘back- scattering’, which is what causes electrical resistance in conventional electrical conductors.” Unlike conventional electrical conductors, such topological edge paths can carry electrical current with near- zero dissipation of energy, meaning that topological transistors could burn much less energy than conventional electronics. They could also potentially switch much faster. Topological materials would form a transistor’s active ‘channel’ component, and would switch between open (0) and closed (1) to accomplish the binary operation used in computing. Research team: Dr Mark Edmonds, PhD student James Collins, Prof Michael Fuhrer (Monash).27 FLEET 2018 ANNUAL REPORT The electric field induces a quantum transition from topological insulator to conventional insulator. To be a viable alternative to current, silicon-based technology (CMOS), topological transistors must: • operate at room temperature (without the need for expensive supercooling) • ‘switch’ between conducting (1) and non-conducting (0) • switch extremely rapidly, by application of an electric field. While switchable topological insulators have been proposed in theory, this is the first time that experiment has proved that a material can switch at room temperature, which is crucial for any viable replacement technology. (In this study, experiments were conducted at cryogenic temperatures, but the large bandgap measured confirms that the material will switch properly at room temperatures.) The material Na 3 Bi is a topological Dirac semimetal (TDS). These materials have long been considered promising systems in which to look for topological field-effect switching, as they lie at the boundary between conventional and topological phases. The study found that when Na 3 Bi is made ‘atomically thin’ (that is, only a few layers of atoms in thickness), it is possible to open an electronic band gap, turning the material into an insulator. This bandgap is an essential component in any electronic switch. Crystal growth and measurements were conducted in FLEET’s laboratories at Monash University, and at the Advanced Light Source (Lawrence Berkeley National Laboratory), in California, where ARPES (angle-resolved photoemission spectroscopy) measurements were made. Research was also undertaken at the Australian Synchrotron. This addresses FLEET milestone 1.1; see p93. The study was published in Nature in December 2018, vol. 564 (see publication 10, p104) . COLLABORATING FLEET PERSONNEL: • Associate Investigator Mark Edmonds (Monash) • PhD student James Collins (Monash) • Partner Investigator Anton Tadich (Australian Synchrotron) • PhD student Chang Liu (Monash) • Associate Investigator Shaffique Adam (Yale-NUS) • Chief Investigator Michael Fuhrer (Monash) NEW PHYSICS: TOPOLOGICAL MATERIALS AND THE 2016 NOBEL PRIZE IN PHYSICS Topological materials represent a paradigm shift in material science, first proposed in 1987 and only demonstrated in the lab in the last decade. The quantum anomalous Hall effect (QAHE) was achieved in the laboratory at Tsinghua University in 2013 by Prof Qi-Kun Xue, now a FLEET Partner Investigator and leading the Centre’s collaboration with Tsinghua University. This 2013 discovery showed that current could be carried with no measurable dissipation and opened up the field of topological electronics being investigated at FLEET. The importance of topological materials was recognised by the 2016 Nobel Prize in Physics, awarded to Michael Kosterlitz, Duncan Haldane and David Thouless. More at FLEET.org.au/topological-switchingNext >