Rice University (online)
The in-person workshop is postponed to November 15-17, 2021. Further details will be provided at a later time.
In the meantime, we are organizing Part I – Virtual Mini-Workshop, April 26-29, 2021. This online event will consist of a small number of talks that are longer and more pedagogical than those planned for the November in-person workshop. We will have one talk each morning, 10:30-11:30am US CDT, during that week. The mini-workshop shares the same focus of the main event, namely, bringing together the band topology and correlated electron communities to highlight the recent advances in different topics, and to provide a forum for cross-talk among the subjects.
Register in advance for Part I - Virtural Mini-Workshop, April 26-29, 2021:
https://riceuniversity.zoom.us/meeting/register/tJcqfuqvrDMsG9y4-igxscWcAXz9k8i1GLlC
After registering, you will receive a confirmation email containing information about joining the meeting.
Part I - Virtual Mini-Workshop
Agenda
Each talk will be for 45 minutes, plus 15 minutes of discussion
All times listed — US CDT
Monday April 26
10:30-11:30am Jennifer Cano (Stony Brook)
"Topological quantum chemistry”
Video Link: https://www.youtube.com/watch?v=-aSTTyes5jI
Tuesday April 27
10:30-11:30am Peter Armitage (Johns Hopkins)
"Electrodynamics of topological materials across the correlation spectrum”
Video Link: https://www.youtube.com/watch?v=5mjymTC3Bhw
Wednesday April 28
10:30-11:30am Silke Paschen (TU Vienna)
"Correlation-driven topological semimetals”
11:30am-12:30pm Andrea Young (UCSB)
"Orbital magnetism in moire heterostructures”
Thursday April 29
10:30-11:30am Nick Butch (U. Maryland)
"Correlated topological superconductivity in UTe2"
Video Link: https://www.youtube.com/watch?v=FX2pmAq_-rw
Abstracts:
Jennifer Cano (Stony Brook)
Topological Quantum Chemistry
I will give an introduction to the theory of Topological Quantum Chemistry. This theory connects topology, which is usually classified in momentum space, with the real space classification of crystals. I will describe how this theory sheds new light on known TIs and demonstrate its power to predict new topological materials. I will then discuss more recent developments and possible extensions to correlated materials.
Peter Armitage (Johns Hopkins)
Electrodynamics of topological materials across the correlation spectrum
In this talk I will discuss recent progress in characterizing the electrodynamic response of topological materials. Some of the most remarkable demonstrations of topological states of matter come through their response to electromagnetic fields. Quantum Hall systems show quantized Hall resistances that are precise to better than one part in a billion and topological insulators are characterized by a quantized magnetoelectric effect. In this talk I will discuss what we have learned about the electrodynamic response of uncorrelated topological states of matter, what we know about the response of systems with moderate correlations, and speculate a bit about what we might find in strongly correlated states.
Silke Paschen (TU Vienna)
Correlation-driven topological semimetals
The insight that nontrivial topology can be implemented in electronic materials via special configurations of their electronic bands has revolutionized condensed matter science. The broad bands of weakly interacting materials and their good description with density functional theory have been instrumental to visualize topological bandstructures (by ARPES). To pin down unique topological properties or even control them – the ultimate goal for topological quantum devices – does, however, remain a formidable challenge. This is where strongly correlated electron systems come into play. As evidenced for the noncentrosymmetric and nonsymmorphic heavy fermion material Ce3Bi4Pd3 [1], strong electron correlations can drive ``extreme topological responses’’ [2-4]. Furthermore, the excellent tunability of strongly correlated electron systems in terms of their correlation physics [5] appears to also allow to control the topological characteristic of these systems [6]. In this talk I will discuss the background, with focus on strong correlation phenomena, present results on Ce3Bi4Pd3, and discuss implications, noting also the possible involvement of quantum criticality in stabilizing correlation-driven topological phases [7].
[1] S. Dzsaber, L. Prochaska, A. Sidorenko, G. Eguchi, R. Svagera, M. Waas, A. Prokofiev, Q. Si, and S. Paschen, Kondo insulator to semimetal transformation tuned by spin-orbit coupling, Phys. Rev. Lett. 118, 246601 (2017).
[2] H.-H. Lai, S.E. Grefe, S. Paschen, and Q. Si, Weyl–Kondo semimetal in heavy-fermion systems, PNAS 115, 93 (2018).
[3] S. Dzsaber, X. Yan, M. Taupin, G. Eguchi, A. Prokofiev, T. Shiroka, P. Blaha, O. Rubel, S.E. Grefe, H.-H. Lai, Q. Si, and S. Paschen, Giant spontaneous Hall effect in a nonmagnetic Weyl-Kondo semimetal, PNAS 118, e2013386118 (2021).
[4] S.E. Grefe, H.-H. Lai, S. Paschen, and Q. Si, Weyl-Kondo semimetals in nonsymmorphic systems, Phys. Rev. B 101, 075138 (2020).
[5] S. Paschen and Q. Si, Quantum phases driven by strong correlations, Nat. Rev. Phys. 3, 9 (2021).
[6] S. Dzsaber, D.A. Zocco, A. McCollam, F. Weickert, R. McDonald, M. Taupin, X. Yan, A. Prokofiev, L.M.K. Tang, B. Vlaar, L. E. Winter, M. Jaime, Q. Si, and S. Paschen, Controlling correlation-driven electronic topology, arXiv:1906.01182.
[7] W. T. Fuhrman, A. Sidorenko, J. Hänel, H. Winkler, A. Prokofiev, J. A. Rodriguez-Rivera, Y. Qiu, P. Blaha, Q. Si, C. L. Broholm, and S. Paschen, Pristine quantum criticality in a Kondo semimetal, arXiv:2007.09460.
Andrea Young (UCSB)
Orbital Magnetism in moire heterostructures
I will describe experiments probing magnetic states based on the spontaneous alignment of electron orbitals. Such orbital ferromagnetism may be a generic phenomena, but has, to date, found its fullest expression in graphene heterostructures in which the two dimensional orbits of electrons in distinct momentum space valleys provide the underlying degree of freedom. As an elementary example I will show data from rhombohedral trilayer graphene, where band edge van Hove singularities lead to a cascade of transitions between metallic ferromagnetic states distinguished by different broken valley and spin symmetries. Adding a moire potential to the trilayer by hBN alignment allows for energy gaps at finite density when the underlying degeneracy of the Fermi surface matches the superlattice filling factor. Because orbital degrees of freedom arise directly from the band wavefunctions, they are uniquely susceptible to experimental control via materials design and new forms of magnetic control using in situ knobs. I will show examples from a variety of moiré heterostructures where magnetic moments, and the resulting quantized anomalous Hall effects, can be tuned using electric currents and the electric field effect. Finally, I will conclude with an outlook for realizing more exotic topological phases of matter based on orbital magnetism.
Nick Butch (U. Maryland)
Correlated Topological Superconductivity in UTe2
We recently discovered a new superconducting state in UTe2 below 1.6 K. This state emerges from a heavy fermion normal state, coexists with strong spin fluctuations, has an extremely high upper critical field of 35 T, and supports an even higher-field reentrant superconducting phase between 40 T and 65 T. In this talk, I will describe how superconductivity in UTe2 dramatically differs from conventional superconductivity, and argue that current evidence suggests that it is topologically nontrivial.
- Ran, C. Eckberg, Q.-P. Ding, Y. Furukawa, T. Metz, S. R. Saha, I-L. Liu, M. Zic, H. Kim, J. Paglione, and N. P. Butch, "Nearly ferromagnetic spin-triplet superconductivity," Science 365, 684 (2019).
- Ran, I-L. Liu, Y. S. Eo, D. J. Campbell, P. Neves, W. T. Fuhrman, S. R. Saha, C. Eckberg, H. Kim, D. Graf, F. Balakirev, J. Singleton, J. Paglione, and N. P. Butch, “Extreme magnetic field-boosted superconductivity,” Nature Physics 15, 1250 (2019).
Part II (In-person) - RCQM Workshop on Topological Materials and Electron Correlations
Preliminary program as of March 4, 2021
N.B.: This program for the November in-person event will be revised and expanded in Fall 2021. The plan for the expanded program is to start on Monday November 15, in the morning, and run through Wednesday November 17, until the mid-afternoon.
Invited talk: 20 + 10 minutes
Contributed talk: 12+3 minutes
Monday November 16, 2021
Coffee, light breakfast and registration (8:00am-8:30am)
Welcome Session
8:30-8:45 Opening Remarks
Session I -- Band topological metals
8:45-9:15 Jennifer Cano (Stony Brook U.)
“Symmetry protected topological semimetals”
9:15-9:45 Peter Armitage (Johns Hopkins U.)
“Electrodynamic response of topological semimetals”
9:45-10:15 Nigel Hussey (Radboud U, the Netherlands)
“Quantum oscillation studies of correlated Dirac semi-metals”
10:15-10:45 Coffee break
Session II -- Topological metals from strong correlations
10:45-11:15 Silke Paschen (TU Vienna, Austria)
“Giant spontaneous Hall effect and field tuning of the Weyl-Kondo semimetal
Ce3Bi4Pd3”
11:15-11:45 Sarah Grefe (Rice U.)
“Weyl-Kondo semimetal: the role of space-group symmetry and control
by magnetic field”
11:45-12:00 Tomoya Asaba (Los Alamos)
“Contributed: Colossal transverse response from non-centrosymmetric
kagome ferromagnets”
12:00-12:15 Blitz poster preview (1 minute per poster)
12:15-1:45 Lunch and Poster Session I
Session III --
“Exploring possible topological physics in two-dimensional magnetic systems”
2:15-2:45 Lebing Chen (Rice U.)
“Topological spin excitations in honeycomb ferromagnet CrI3”
2:45-3:15 Nandini Trivedi (Ohio State)
“Magnetic field-induced intermediate quantum spin liquid with a spinon Fermi surface”
3:15-3:30 Martin Rodriguez-Vega (UT-Austin)
“Contributed: Low-frequency driven systems -- effective Hamiltonians and control of
ordered phases of matter”
3:30-4:00 Coffee break
Session IV -- Topology and strong correlations
4:00-4:30 Steffen Wirth (Max Planck Dresden, Germany)
“Scanning tunneling spectroscopy on topological materials”
4:30-5:00 Jenny Hoffman (Harvard U.)
“Imaging emergent heavy Dirac fermions of a topological Kondo insulator”
5:00-5:30 Meigan Aronson (UBC)
“Chiral Surface States in HfNiSn”
5:30-6:00 Hans-Peter Buechler (U. Stuttgart, Germany)
“Observation of a symmetry protected topological phase of interacting bosons with
Rydberg atoms”
November 17, 2021
Coffee, light breakfast and registration (8:00am-8:30am)
Session V -- Band topology and phase transitions
8:30-9:00 Joel Moore (UC Berkeley)
“Origins of strong and/or quantized nonlinear optical responses in Weyl semimetals”
9:00-9:30 Yulin Chen (Oxford U., UK)
“Visualize and control topological electronic structures in metallic phases”
9:30-10:00 Jiun-Haw Chu (U. Washington – Seattle)
“Strain tuned topological phase transition in ZrTe5”
10:00-10:15 Jianwei Huang (Rice U.)
“Contributed: Phase transition in quasi-one-dimensional topological insulators”
10:15-10:45 Coffee break
Session VI -- Topology and superconductivity
10:45-11:15 Nick Butch (U. Maryland)
“Correlated topological superconductivity in UTe2”
11:15-11:45 Anne de Visser (U. Amsterdam, the Netherlands)
“Nematic superconductivity in topological materials”
11:45-12:15 Tsz Chun Wu (Rice U.)
“Electromagnetic responses in a topological superconductor and Weyl superconductor
due to surface states”
12:15-12:30 Blitz poster preview (1 minute per poster)
12:30-2:00 Lunch and Poster Session II
Session VII – Graphene moiré bands
2:00-2:30 Andrea Young (UC Santa Barbara)
“A twisted perspective on moiré heterostructures”
2:30-3:00 T. Senthil (MIT)
“Correlations and topology in graphene moiré lattices”
3:00-3:30 Coffee break
Session VIII – From materials to information
3:30-4:00 Jim Sauls (Northwestern)
“Signatures of broken time-reversal & mirror symmetries in topological
superconductors”
4:00-4:30 Paul C. W. Chu (U. Houston)
“Retention of the high-pressure-induced superconducting phase in Sb at ambient”
4:30-5:00 Andrew Potter (UT Austin)
“Quantum algorithms for holographic simulation of correlated and topological states”
Session IX – Discussion on opportunities and prospects
5:00-5:30 Rapporteurs: Peter Armitage and Silke Paschen
Rationale and Scope:
There have been extensive recent advancements on topological materials, both in weakly correlated settings and in strongly interacting systems. Among these are discovery and exploration of new topological states of matter and their transitions to nearby quantum phases. The breadth of the field calls for interactions among the different sub-communities. This workshop aims to bring together top experts from these communities to highlight the recent achievements in each area, and to provide a forum for cross-talk among the subjects.
The workshop will revolve around the following focus areas in the overarching field of Topological Materials:
- Symmetry-protected Semimetals
- Topological States in Magnets and Superconductors
- Topological States Driven by Strong Correlations
- Strong Correlation Physics for Topology
- Tuning Topological States
- Diverse Materials and Broader Contexts
The total number of invited speakers will be about 20.
Tentative List of Sessions and Invited Speakers:
Recent developments on band topology
Topological metals driven by strong correlations
Topology in magnetic systems
Topological superconductors
Tuning topological states
Graphene moiré bands
Diverse materials
Broader contexts: from materials to information
Peter Armitage (Johns Hopkins U.)
Meigan Aronson (UBC)
Hans-Peter Büchler (U. Stuttgart)
Nick Butch (U. Maryland)
Jennifer Cano (Stony Brook U.)
Lebing Chen (Rice U.)
Yulin Chen (Oxford U.)
Jiun-Haw Chu (U. Washington, Seattle)
Anne de Visser (U. Amsterdam)
Sarah Grefe (Rice U.)
Jenny Hoffman (Harvard U.)
Nigel Hussey (Radboud U)
Joel Moore (UC Berkeley)
Silke Paschen (Vienna U. of Technology)
Andrew Potter (UT Austin)
Jim Sauls (Northwestern)
T. Senthil (MIT)
Nandini Trivedi (Ohio State U.)
Steffen Wirth (Max Planck, Dresden)
Tsz Chun Wu (Rice U.)
Andrea Young (UCSB)
Paul C. W. Chu (U. Houston)
Format:
The workshop will last for two days, incorporating 30min invited speaker slots as well as two poster sessions. Several contributed talks will be selected from submitted posters.
Organizers:
Pengcheng Dai (Rice University)
Matt Foster (Rice University)
Qimiao Si (Rice University)
Ming Yi (Rice University)
For questions on the scientific program, please contact one of the organizers.
For accommodation and other logistics questions, please contact Ginny Whitaker at 713-348-2980.