Plastic semiconductors incorporated into transistors have shown enormous potential for low-cost, flexible, printable electronics and bioelectronics. In my talk, I will discuss their history, operating mechanisms, and potential applications. I will highlight key challenges to these applications, and discuss some of the approaches I've taken to overcome them. I will show how these simple solutions can work towards the broad realization of organic transistors.

Carbon Based Nano Electromechanics: Physics and Applications

Sang Wook Lee

Department of Physics, Ewha Womans University, Seoul, 03760, Korea

E-mail: leesw@ewha.ac.kr

In this presentation, physical properties and possible applications of carbon based nano electro-mechanical devices

(NEMS) will be introduced. Our research started from carbon nanotube based nano electro-mechanical relay

structure and expanded to graphene-based xylophone and drum like devices. Micro contact transfer method is

applied to realize the suspended nano structures with various electrodes under the nano materials. Recently

developed pick-up and transfer technique made us possible to fabricate various stacking and suspended nano

structures. After introducing some interesting physical properties, such as basic mechanical switching and

resonance behaviour and light emission of suspended graphene structures, possible application of carbon based

nano electro-mechanical devices will be suggested. Graphene based ultra-sensitive mass detector will be suggested

for one of the promising applications of our devices and our recent research project on single protein sequencing

using graphene-based mass detector will be introduced at the end of presentation.

Dr. Ankur Das

Postdoctoral Research Associate

Weizmann Institute of Science

Rehovot, Israel

Title: Detection of 5/2 phases

Abstract: The phases of the \nu=5/2 state have been shown to be very elusive but one of the most interesting ones as it is proposed to contain Majorana modes with non-abelian statistics. There is more than one candidate for the non-abelian state and among that three are the most promising ones namely pfaffian, anti-pfaffian, and particle-hole symmetric pfaffian. Quite a few experiments later the issue has not been settled. Previous efforts proposed methods to distinguish the candidates including the proposals where the order can be determined by measuring both thermal conductances and shot noise on the same device [Park et al. PRL 125, 157702 (2020)] or by only measuring the unequilibrated electrical conductance [Yutushui et al. PRL 128, 016401 (2022)]. To avoid some of the experimental challenges and limitations of the proposals including the above-mentioned ones we propose a new device made out of interfaces of the \nu=5/2 state and Abelian states. We propose to measure electrical shot noise to resolve among these states.

Professor John Davis

Associate Professor

University of Alberta

Department of Physics

Title:  Superfluid Helium Electromechanics

Abstract: Liquid helium posses many properties that make it an attractive medium for studies of mechanical systems in the quantum regime, such as low mechanical and dielectric losses.  The flip side of this is to imagine using optomechanics or electromechanics to revisit the novel physics of superfluid helium, including bosonic helium-4 and fermionic helium-3.  In particular, when spatially restricted in one dimension, helium superfluids are expected to demonstrate quasi-two dimensional behavior with qualitatively different physics than in three dimensions.  By using nanofabrication techniques to both confine the helium and provide an electromechanical detection scheme, we are beginning the journey of studying such two-dimensional superfluids.

Dr. Allen Scheie

Postdoctoral Research Associate

Oak Ridge National Laboratory

Neutron Scattering Division

Title: Witnessing entanglement in quantum magnets using neutron scattering

Abstract: In this talk I show how information about solid state quantum entanglement can be extracted from magnetic neutron scattering using model-independent techniques. Using the 1D spin chain KCuF3, we examine three entanglement witnesses applicable to neutron scattering: one tangle, two tangle, and Quantum Fisher Information (QFI). We find that QFI is the most experimentally robust, giving good agreement between theory and experiment over all measured temperatures, and witnessing multipartite entanglement up to 75 K. We then apply the entanglement witnesses to the 2D triangular lattice KYbSe2, showing the presence of appreciable entanglement in the low temperature phase. We then use diffuse scattering fits, heat capacity comparisons, and nonlinear spin wave fits to demonstrate that KYbSe2 is proximate to a quantum spin liquid. We thus provide a rigorous route to studying and understanding highly entangled quantum phases.

Professor Jun Hee Lee

School of Energy and Chemical Engineering

Ulsan National Institute of Science and Technology

South Korea

Title: Ultimate-density atomic semiconductor via flat phonon bands

Abstract: Dispersion-less flat energy bands in momentum space generate localized states and are known to cause unconventional phenomena such as graphene superconductivity in electrons and individual spin flips in magnons. However flat bands in phonon were not discovered yet. For the first time, we discovered flat bands in phonon exist surprisingly in a ferroelectric HfO₂ and produce a localized motion of atoms as if their chemical bond temporarily disappears by an external voltage. With the vanishing bond, each atom can be freely displaced by the voltage for the information storage. Our discovery of the atom control directly in a solid will lead us to the design of ultimate-density memory semiconductors reaching up to ~100 TB [1]. Our theory is directly applicable to the Si-compatible HfO₂ so can be materialized in all electronic devices [2]. Just as Einstein’s theory of relativity (E=mc²) enabled us to make bombs out of atoms not out of materials, with our “Atomic Semiconductor” we will open the era of designing memories on an atomic scale rather than a materials scale and carrying a data center in the palm of your hand.

[1] “Scale-free ferroelectricity driven by flat phonon bands in HfO₂”, H.-J. Lee et al., Science 369, 1343 (2020).

[2] “A key piece of the ferroelectric hafnia”, B. Noheda et al., Science 369, 1300 (2020).

Professor Dima Pesin

Associate Professor

University of Virginia

Title: Optical and transport properties of metals with nontrivial band geometry

Abstract: I will describe how the geometry of the band structure of metals manifests itself in their optical and transport properties. I particular, I will discuss optical Hall response of chiral crystals in the presence of a DC transport current – the gyrotropic Hall effect – and show that it is related to the Berry curvature dipole. The latter fact makes the gyrotropic Hall effect a diagnostic tool for topological properties of three-dimensional chiral metals. I will also talk about manifestations of band geometry is electron-electron collisions, and the ensuing anomalous Hall effect in the hydrodynamic regime.

Dima Pesin

Associate Professor of Physics

University of Virginia

Title: TBA

Abstract: TBA

Dr. Eslam Khalaf

University of Texas-Austin

Title: Strong Coupling Theory of Magic-Angle Graphene

Abstract: In this talk, I will review a recently developed strong coupling theory of magic-angle twisted bilayer graphene. An advantage of this approach is that a single formulation can capture the insulating and superconducting states, and with a few simplifying assumptions, can be treated analytically. I begin by reviewing the electronic structure of magic angle graphene’s flat bands, in a limit that exposes their peculiar band topology and geometry. I will show how similarities between the flat bands and the lowest Landau level can provide valuable insights into the effect of interactions and form the basis for an analytic treatment of the problem. At certain fractional fillings, the similarity to Landau level physics suggests a promising route for realizing fractional Chern insulators. At integer fillings, this approach points to flavor ordered insulators, which can be captured by a sigma-model in its ordered phase. Remarkably, topological textures of the sigma model carry electric charge which enables the same theory to describe the doped phases away from integer filling. I will show how this approach can lead to superconductivity on disordering the sigma model, and estimate the Tc for the superconductor. I will highlight the important role played by an effective super-exchange coupling both in pairing and in setting the effective mass of Cooper pairs. At the end, I will show how this theory provides criteria to predict which multilayer graphene stacks are expected to superconduct including the recently discovered alternating twist trilayer platform.

Oksana Ostroverkhova

Professor of Physics

Oregon State University

Title: Photophysics of organic materials: from ancient pigments to high-performance organic semiconductors

Abstract: Organic (opto)electronic materials have been explored in a variety of applications in electronics and photonics. They offer several advantages over traditional silicon technology, including low-cost processing, fabrication of large-area flexible devices, and widely tunable properties through functionalization of the molecules. Over the past decade, remarkable progress in the material design has been made, which led to a considerable boost in performance of organic thin-film transistors, solar cells, and other applications that rely on photophysics and/or (photo)conductive properties of the material. Nevertheless, a number of fundamental questions pertaining to light-matter interactions and charge carrier photogeneration and transport in these materials remain. In this presentation, I will give examples of our efforts aiming to understand and tune exciton, polariton, and charge carrier dynamics in high-performance organic materials and to develop novel, sustainable organic materials.