Upcoming Events For Colloquia

Physics Colloquium

Synthesizing and visualizing Majorana modes

Dr. Ilya K. Drozdov
Assistant Scientist at the Condensed Matter Physics and Materials Science Division
Brookhaven National Laboratory

In this talk, I will give an introduction to topological phases of matter, topological superconductivity, and, more specifically, excitations of a topological superconductor known as Majorana modes. I will discuss experimental progress in realizing topological phases in materials and observing spectroscopic signatures of those phases with the focus on scanning tunneling microscopy (STM) experiments. One example of such behavior is found in elemental Bismuth, a material that attracted a lot of attention due
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Physics Colloquium

Orbital Chern insulators in flat-band graphene moiré systems

Dr. Hryhoriy Polshyn
Postdoctoral Scholar, Department of Physics
University of California Santa Barbara

Taming topological electronic phases is one of the central problems of modern condensed matter physics and a prerequisite for new technologies such as topological quantum computation. Realizing topological phases at zero magnetic field has been a longstanding goal since Haldane’s theoretical proposal of the quantum anomalous Hall (QAH) state. My talk will focus on newly discovered QAH states that emerge in twisted bilayer and trilayer graphene systems. In contrast to magnetically doped topological insulators, the QAH states in these moiré systems are driven by intrinsic strong interactions, which polarize the electrons into a single moiré miniband with Chern number of C = 1 or 2. Remarkably, the magnetization of these “orbital Chern insulators” (OCI) arises predominantly from the orbital motion of the electrons rather than the electron spin. I will discuss a novel effect originating from the curious magnetic properties of OCIs that enables non-volatile electrical switching of the magnetic and topological orders. Finally, I will present recent studies of the OCIs that emerge at half-fillings of moiré minibands and spontaneously break the moiré superlattice symmetry.…

Physics Colloquium

Visualizing Electron-Pair Fluids and Crystals at the Atomic Scale

Dr. Xiaolong Liu
Kavli Fellow, Physics
Cornell University

Pairing of electrons with opposite momenta takes place inside most conventional superconductors, leading to translationally invariant fluids of electron pairs. Meanwhile, electron pairs can form crystals known as pair density waves (PDWs) that break translational symmetry. Experimental evidence of PDWs, however, remains scarce due to the difficulty in imaging the superconducting condensate. In this talk, I will first introduce our recent discovery of a PDW state in a transition metal dichalcogenide, NbSe 2 , using atomic-resolution scanned Josephson-tunneling microscopy (SJTM). We observe two characteristic signatures of PDWs including periodic modulations of electron-pair density and superconducting energy gap at the wavevectors of preexisting charge density waves. Using the same SJTM technique, I will then discuss our capability in visualizing the velocity field and supercurrent density of electron-pair fluid flow around quantum vortices. Finally, I will share my perspective on applications of such novel techniques in other emerging quantum materials.…

Physics Colloquium

Synthesizing, Understanding, and Controlling Quantum Materials

Dr. Na Hyun Jo
Postdoctoral Researcher, Quantum System Accelerator
Lawrence Berkeley National Laboratory

We are currently living on the edge of the silicon age, characterized by the rapid growth of the semiconductor industry. Yet, a new class of materials destined to become as familiar as silicon is underway. These materials are so-called quantum materials and will be very important for future technologies such as quantum computers. In order to use quantum materials for future applications, it is essential to understand and control their electrical properties. In this colloquium, I will present synthesizing, understanding, and controlling a quantum material, WTe₂…

Physics Colloquium

Structural control of quantum materials with light

Dr. Ankit S. Disa
Condensed Matter Dynamics Department
Max Planck Institute for the Structure and Dynamics of Matter

Quantum materials exhibit unique macroscopic phenomena with enormous technological potential, ranging from high-temperature superconductivity to topologically protected transport. Hence, at the forefront of condensed matter research is the goal of understanding and controlling their emergent behavior at the smallest length and time scales possible. Due to the strongly intertwined nature of electrons and the crystal lattice in these materials, manipulating the atomic structure allows one to tune interactions and create novel electronic and magnetic phases.…

Title TBA

Prof. Keith Baker
Yale University

Abstract forthcoming.…

Title and abstract forthcoming

Ms. Lauren Chambers
ACLU of Massachusetts

All interested persons are invited to attend remotely—email physics@nd.edu for information.…

Physics Colloquium

Title and abstract forthcoming

Prof. Nico Orce
University of the Western Cape

Hosted by Prof. Brodeur

All interested persons are invited to attend remotely—email physics@nd.edu for information.…

Title and abstract forthcoming

Prof. Louise Edwards
California Polytechnic State University

All interested persons are invited to attend remotely—email physics@nd.edu for information.…

Title and abstract forthcoming

Dr. Rebecca Thompson
Head of Education and Public Engagement
Fermilab

Hosted by Prof. Brodeur

All interested persons are invited to attend remotely—email physics@nd.edu for information.…