Quantum Matter Working Group 2019

 Investigating problems in quantum materials

 

Contact  

  • Director
  • Dr. Filip Ronning
  • Institute for Materials Science
  • (505) 667-7426
  • Email
  • Administrator
  • Kelly Shea
  • Institute for Materials Science
  • (505) 667-9244
  • Email

Quantum-Matter-BLANK-Slide-7_1_2019.jpg

Emerging problems in quantum materials

The IMS at LANL is convening a “quantum matter working group” to work on emerging problems in quantum materials, and simultaneously help define Los Alamos’s agenda on quantum matter for the coming year. We will focus our efforts for 3 weeks between July 14th and August 2nd. We expect to build a fun and creative atmosphere for generating new ideas. LANL has rich and diverse efforts in quantum materials including the 100 T pulsed magnetic field facility, the correlated f-electron materials group, ultrafast optics, topological materials, quantum information science, theory division, the Center for Integrated Nano-Technologies, the Center for Non-Linear Studies, and the IMS. Topical discussions are likely to focus on opportunities for these areas of research. We anticipate having 10-20 external visitors coupled with an equal number of LANL staff participating.

List of participants

• Peter Abbamonte, University of Illinois Urbana-Champagne, week of July 29th
• Richard Averitt, University of California - San Diego, July 30th - 31st
• Alexander Balatsky - University of Connecticut/NORDITA, TBD
• Kevin Bedell - Boston College, July 25th - August 2nd
• Stuart Brown, University of California - Los Angeles, TBD
• Jennifer Cano, Stony Brook University - New York, week of July 22nd
• Yong Chen, Purdue University, July 30th - August 1st
• Zach Fisk, University of California - Irvine, July 14th - August 2nd
• Steve Hill, Florida State University, July 17th - 18th
• Ezekiel Johnston-Halperin, Ohio State University, July 23rd - 24th
• Lu Li, University of Michigan, week of July 29th
• Allan MacDonald, University of Texas, week of July 22nd
• Joel Moore, University of California - Berkeley, July 15th - 17th
• Sungwoo Nam, University of Illinois Urbana-Champagne, July 24th - 25th
• Michael Norman, Argonne National Laboratory, week of July 22nd
• Pawel Potasz, Wroclaw Technical University, Poland, week of July 22nd
• Eli Rotenberg, Lawrence Berkeley National Laboratory, July 30th - August 1st
• Yuki Sato, Kyoto University, week of July 29th
• Qimiao Si, Rice University, July 26th - 29th
• Susanne Stemmer, University of California - Santa Barbara, July 23rd - 24th
• Senthil Todadri, Massachusetts Institute of Technology - week of July 29th

Talks by externals coupled with short talks and discussions led by LANL scientists to identify
opportunities in Quantum Materials.

Agenda

Week One:  July 15-19, Sig Hecker Conference Room (TA03-0032-134)

Week one agenda

Mon:   

10:00am – 11:00am Joel Moore, UC Berkeley/Lawrence Berkeley National Laboratory

Origins of strong and/or quantized nonlinear optical responses in Weyl semimetals

This talk starts by reviewing known examples of how topological materials generate new kinds of electrodynamic couplings and effects.  Three-dimensional topological insulators realize a particular electromagnetic coupling known as “axion electrodynamics”, and understanding this leads to an improved  understanding of magnetoelectricity in all materials.  We then turn to how
topological Weyl and Dirac semimetals can show unique electromagnetic
responses; we argue that in linear response the main observable effect
solves an old problem via the orbital moment of Bloch electrons, and how
in nonlinear optics there should be a new quantized effect, which may just
have been seen experimentally.  This nonlinear effect has a natural quantum
e^3/h^2 and appears in chiral Weyl semimetals over a finite range of frequencies.

   11:00pm – 11:20pm   

Jonny Cookmeyer, University of California-Berkeley

Magnon thermal transport and \alpha-RuCl_3

Thurs: 10:30am-11:30am

Steve Hill, Florida State University

Molecular spins for quantum computation

Spins in solids or in molecules possess discrete energy levels, and the associated quantum states can be tuned and coherently manipulated by means of external electromagnetic fields. Spins therefore provide one of the simplest platforms to encode a quantum bit (qubit), the elementary unit of future quantum computers. Performing any useful computation demands much more than realizing a robust qubit—one also needs a large number of qubits and a reliable manner with which to integrate them into a complex circuitry that can store and process information and implement quantum algorithms. This ‘scalability’ is arguably one of the challenges for which a chemistry-based bottom-up approach is best-suited [1]. Molecules, being much more versatile than atoms, and yet microscopic, are the quantum objects with the highest capacity to form non-trivial ordered states at the nanoscale and to be replicated in large numbers using chemical tools.

 

[1]  A. Gaita‐Ariño, F. Luis, S. Hill, E. Coronado, Perspective in Nat. Chem. 11, 301 – 309 (2019); https://doi.org/10.1038/s41557-019-0232-y

 

Fri: 10:00am-11:00am 

Boris Spivak, University of Washington

Anomalous Metals

The observation of metallic ground states in a variety of two-dimensional electronic systems poses a fundamental challenge for the theory of electron fluids. I will analyze evidence for the existence of a regime, which we call the “anomalous metal regime," in diverse 2D superconducting systems driven through a quantum superconductor to metal transition by tuning physical parameters such as the magnetic field, the gate voltage in the case of systems with a MOSFET geometry, or the degree of disorder. The principal phenomenological observation is that in the anomalous metal, as a function of decreasing temperature, the resistivity first drops as if the system were approaching a superconducting ground state, but then saturates at low temperatures to a value that can be orders of magnitude smaller than the Drude value. The anomalous metal also shows a giant positive magneto-resistance. Thus, it behaves as if it were a failed superconductor." This behavior is observed in a broad range of parameters. I will exhibit, by theoretical solution of a model of superconducting grains embedded in a metallic matrix, that as a matter of principle such anomalous metallic behavior can occur in the neighborhood of a quantum superconductor-metal transition. However, I will also argue that the robustness and ubiquitous nature of the observed phenomena are difficult to reconcile with any existing theoretical treatment, and speculate about the character of a more fundamental theoretical framework.

 

Week two: July22-26, Sig Hecker Conference Room (TA03-0032-134)

week two agenda
Mon:    9:30am-9:50am Quantum Materials at LANL overview by Filip Ronning, LANL
9:50am-10:50am

Allan MacDonald, University of Texas

Moire superlattices

10:50am-11:00am Break
11:00am-11:30am

Ming Xie, University of Texas

Topology and Correlations in Magic Angle Twisted Bilayer Graphene

11:30am-12:00pm

Pawel Potasz, Wroclaw Technical University, Poland

Exact Diagonalization Approach to Electronic Correlations  in Magic Angle Twisted Bilayer Graphene

  Lunch (Provided)
2:00pm-3:00pm 

Mike Norman, Argonne National Laboratory

What does second harmonic generation tell us about hidden order?

3:00pm-4:00pm

Alexander Balatsky, University of Connecticut/Nordic Institute for Theoretical Physics (NORDITA)

Dirac Materials and Materials Informatics

I will discuss a class of materials we call Dirac Materials. In the first part I will discuss materials informatics tools we developed to search for new organic functional materials. In the second part of the talk I will discuss the rapid developments in time resolved probes and in manipulation of quantum matter in time domain open opportunities to control correlations and instabilities of electronic states in time domain. Dirac Materials exhibit nodes in the spectra that result in the strong energy dependence of the Density of States (DOS). Hence the driven and nonequilibrium Dirac Materials offer a platform for investigation of collective instabilities of Dirac nodes via controlled tuning of the coupling constants with drive. I will present the results of  investigation of the many body instabilities, like excitonic instabilities, in driven Dirac Materials. Recent optical pump experiments are consistent with the creation of long lived states away from equilibrium in Dirac Materials and hence pave the way to tunable interactions in Dirac Materials.

Tues:   10:00am-11:00am Jennifer Cano, Stony Brook University - Symmetry protected topological semimetals
11:00am-11:15am

Tomo Asaba, LANL

Anomalous Hall effect in U3Ru4Al12

11:15am-12:00pm Discussion: experimental searches for topological materials - Priscila Rosa, LANL

5:30pm BBQ at Filip Ronnings - 1094 Big Rock Loop - Please RSVP to fronning@lanl.gov
Wed: 9:00am-10:00am

Ezekiel Johnston-Halperin, Ohio State University

Quantum devices with room temperature organic magnets

10:00am-10:25am Discussion: soft quantum materials at LANL – Vivien Zapf, LANL
10:25am-10:35am Short break
10:35am-11:35am

SungWoo Nam, University of Illinois at Urbana-Champaign -

Strained Two-dimension Semiconductors for Quantum Emitters

Quantum confinement in atomically-thin transition-metal dichalcogenides (TMDs) has been explored recently for single quantum emitters based on naturally occurring or artificially created defects. In this talk, I will present our work on deterministic straining and confinement of excitons in atomically-thin TMDs for artificial quantum emitters. We show that mechanical straining and confinement in monolayer TMDs are viable solutions to produce precisely controlled single quantum emitters. More specifically, I will present predictable and reconfigurable strain engineering in atomically-thin WSe2 via three-dimensional (3D) wrinkle architectures. Strain exerted on WSe2 was periodically modulated to tensile and compressive strain at peaks and valleys of the wrinkles, respectively via 3D wrinkle architecture. By tuning wrinkling parameters (e.g., prestrain, skin layer thickness) and encapsulation methods, we were able to achieve photoluminescence (PL) emission shift of as much as ~200 meV, corresponding to approximately 4% strain. Furthermore, owing to the deformable nature of the wrinkle architecture, the applied strain can be tuned reconfigurably by post stretching/releasing processes, with PL shift dynamically modulated. Time-resolved PL decay measurements revealed heterogeneous exciton recombination where tensile strain leads to longer exciton lifetime compared to unstrained or compressive strained regions. Finally, I will present our results on localized straining of 2D materials including WSe2 and MoS2 monolayers for single photon emission.

11:35am-12:00pm Discussion: 2D materials at LANL – Jinkyoung Yoo, LANL
2:00pm-3:00pm

Susanne Stemmer, University of California-Santa Barbara

Thin Films of Topological Semimetals and Superconducting SrTiO3.

Thurs: 10:30am-11:30am

Kevin Bedell, Boston College

The Higgs Amplitude mode in the Ferromagnetic Metal MnSi: Where are we now?

11:30am-12:00pm Discussion: non-collinear metallic magnets at LANL – Shizeng Lin, LANL

 

 Week three: July 29-August 2, Sig Hecker Conference Room (TA03-0032-134)

Week three agenda
Mon: Session on Quantum Oscillations in Insulators
9:30am-10:15am

Senthil Todadri, Massachusetts Institute of Technology

Quantum Oscillations in Insulators

10:15am-11:00am

Yuji Sato, Kyoto University, Japan

Thermal transport in YbB12

11:00am-11:10am Break
11:10am-11:55am

Lu Li, University of Michigan

Quantum Oscillations in Insulators

11:55am-12:15pm Sean Thomas, LANL - Possibility of quantum oscillations from flux inclusions
Lunch (provided)
1:40pm-2:00pm Quantum Materials at LANL overview by Filip Ronning, LANL

Session on Kondo Semimetals

2:00pm-2:45pm

Neil Harrison, LANL

Metallization of a Kondo Insulator at a QCP

2:45pm-3:30pm

Qimiao Si, Rice University

Weyl-Kondo semimetal and candidate heavy fermion systems for its realization

3:30pm-4:00pm Discussion - Open questions and opportunities regarding Quantum Oscillations in Insulators – Discussion leader TBD
Tues: 10:00am-11:00am

Peter Abbamonte, University of Illinois-Urbana/Champagne

Quantum Criticality with EELS

11:00am-12:00pm

Joe Thompson, LANL

Open Questions in Quantum Criticality – a 115 perspective

Superconductivity session
1:30pm-2:30pm

Zach Fisk, University of California-Irvine

The chemistry of superconducting materials

2:30pm-3:30pm 

Stuart Brown, University of California-Los Angeles

Elastic tuning of quantum materials: Sr2RuO4 and beyond

3:30pm-3:50pm

Fedor Balakirev, LANL

Hc2 of hydride SC’s under high pressure

Wed: 9:30am-10:00am

Keshav Dani, Okinawa Institute of Science and Technology, Japan

Time Resolved Photoemission Spectroscopies on Semiconductor Systems

Abstract: In the past few decades, Angle resolved photoemission spectroscopy (ARPES) and Photoemission microscopy (PEEM) have been used extensively to study the electronic structure and surface properties of materials. By adding femtosecond time resolution to these techniques, one can visualize the dynamics of the electronic properties with high spatial resolution or within the band structure of the material. In this talk, I will review our recent progress on performing TR-ARPES and TR-PERM on interesting semiconducting systems. 

 

10:00am-11:00am

Rick Averitt, University of California-San Diego

Investigation of coherent magnons in antiferromagnetic iridate Sr2IrO4

Gu-Feng Zhang1, Xiang Chen2, Urban F.P. Seifert3,4, Jingdi Zhang1, Kevin Cremin1, Leon Balents4, Stephen D. Wilson2 and Richard D. Averitt1

        1Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA,  2Materials Department, University of California, Santa Barbara, California 93106, USA 3Institut für Theoretische Physik, Technische Universität Dresden, 01062 Dresden, Germany 4Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106, USA

The spin-orbit coupled Mott insulator Sr2IrO4 has attracted considerable interest because of its exotic Jeff = 1/2 Mott state arising from the interplay of on-site Coulomb repulsion and strong spin-orbit coupling. We have investigated magnetization dynamics of this enigmatic compound. Specifically, we measured coherent magnons of the Jeff = 1/2 Mott state using Kerr rotation following excitation with either mid-infrared 9 μm (below the charge gap), or near-infrared 1.3 μm (above the charge gap) circularly polarized pulses. For both pump wavelengths, the 2D in-plane B2g coherent magnon oscillation of frequency ~0.5 THz is observed. In this talk, we show that the excitation pathways are different for these two excitation wavelengths. In particular, coherent magnon excitation with 9 μm pulses arises from the inverse Faraday effect that, microscopically, is related to two-magnon processes. Notably, coherent magnon generation with 9 μm pulses is nearly an order of magnitude more efficient in comparison to 1.3 μm pulses, without excitation of carriers across the Mott gap.

Acknowledgement: This research is supported by the Army Research Office MURI grant ARO W911NF-16-1-0361, “Floquet engineering and metastable states.”

 

11:00am-11:40am Discussion: Driven Quantum Matter at LANL – Rohit Prasankumar, LANL
2:30pm-3:30pm

Eli Rotenburg, Lawrence Berkeley National Laboratory

Micro and nano ARPES on 2D materials

 

3:30pm-4:30pm

Yong Chen, Purdue University

Towards topological superconductors and semimetals from topological insulators

 

Thurs: 10:00am-10:30am

Dan Mao, Massachusetts Institute of Technology

Anomalous quantum Hall effects in graphene moire structures

 

10:30am-11:00am

Marein Rahn, LANL

CePd3 RIXS