Condensed Matter Seminars

Investigating the Role of Disorder, Electron Concentration, and Lattice Compression in Uranium-based Heavy Fermion Systems

Speaker: 
Eteri Svanidze, McMaster University
Event Date and Time: 
Thu, 2017-05-25 14:00 - 15:00
Location: 
Hennings 318
Local Contact: 
Ian Affleck
Intended Audience: 
Graduate

Uranium intermetallic compounds exhibit a wide range of exotic properties -- unconventional superconductivity and quantum criticality, complex magnetic configurations, as well as heavy fermion and non-Fermi liquid behaviors. Moreover, while all of these phenomena are related to the degree of localization of the 5f electronic states, the complete understanding of underlying mechanisms is still lacking, explaining the unceasing interest in heavy fermion systems.

Observing a Scale Anomaly in Graphene : a Universal Quantum Phase Transition

Speaker: 
Eric Akkerman, The Technion, Israel
Event Date and Time: 
Thu, 2017-08-03 14:00 - 15:00
Location: 
Hennings 318
Local Contact: 
Ian Affleck
Intended Audience: 
Graduate
Scale invariance is a common property of our everyday environment. Its breaking gives rise to less common but beautiful structures like fractals. At the quantum level, breaking of continuous scale invariance is a remarkable exemple of quantum phase transition also known as scale anomaly. The general features of this transition will be presented at an elementary quantum mechanics level. Then, we will show recent experimental evidence of this transition in graphene.

Field induced phase transition in one dimensional Heisenberg antiferromagnet model studed using density matrix renormalization group

Speaker: 
Peter Gustainis, Affleck group, UBC
Event Date and Time: 
Fri, 2017-03-31 13:00 - 14:00
Location: 
Hennings 309
Local Contact: 
Ian Affleck

This presentation will examine the Heisenberg antiferromagnetic
spin chain in one dimension (1D) with a crystal field splitting term and applied
magnetic field term. We use theoretical techniques from quantum field
theory and conformal field theory (CFT) to make predictions about the
excitation spectrum for our model. We then use Density Matrix
Renormalization Group (DMRG) numerical techniques to simulate our spin
chain and extract the energy spectrum as we vary our crystal field

Constrained Path Monte Carlo: recent development and application

Speaker: 
Mingpu Qin (College of William and Mary)
Event Date and Time: 
Thu, 2017-03-23 14:00 - 15:00
Location: 
Hennings 318
Local Contact: 
Marcel Franz
Intended Audience: 
Graduate

 

Special Condensed Matter Seminar

Speaker: 
Norman Tubman
Event Date and Time: 
Fri, 2017-03-03 15:00 - 16:00
Location: 
Hennings 304
Local Contact: 
Marcel Franz
Intended Audience: 
Graduate

Strongly correlated systems are some of the most difficult to simulate with electronic structure methods. The most widely used techniques, for simulating realistic materials, lose their predictive power when electron correlations are important. For example, there remain many open questions about the electronic properties of the high temperature superconducting cuprate materials.

Orbital and magnetic excitations in the spin-chain compound TiPO4

Speaker: 
Jochen Geck, Institute of Structural Physics, TU Dresden, Germany
Event Date and Time: 
Thu, 2017-03-02 14:00 - 15:00
Location: 
Hennings 318
Local Contact: 
George Sawatzky

We present high-resolution resonant inelastic x-ray scattering data as well many-body quantum chemistry calculations for the spin-chain compound TiPO4. This combined approach allows identifying the d-level electron configuration of Ti in this material, which is found to be at odds with canonical local ligand-field theory. Specifically, we find the ground state to be composed of an admixture of z2 and zx orbitals, highly unusual for six-fold coordinated d-metal sites.

Mott Insulator versus Bose glass in nanostructured Josephson junction chains

Speaker: 
Timothy Duty, EQuS - ARC Centre for Engineered Quantum Systems and School of Physics, University of New South Wales
Event Date and Time: 
Thu, 2017-02-16 14:00 - 15:00
Location: 
Hennings 318
Local Contact: 
Doug Bonn
Intended Audience: 
Graduate
The low-temperature states of bosonic condensates exhibit fundamental quantum
effects at the macroscopic scale such as supercurrents. The combined effects of
interaction and disorder in these can have drastic consequences, leading to the
Mott insulator and Bose-Anderson glass. The latter is thought to describe helium-4
in porous media, cold atoms in disordered optical potentials, disordered magnetic
insulators, and thin superconducting films.

Dopants and Charge Carriers in Colloidal Quantum Dots

Speaker: 
Daniel R. Gamelin, Department of Chemistry, University of Washington
Event Date and Time: 
Thu, 2017-05-18 14:00 - 15:00
Location: 
Hennings 318
Local Contact: 
Curtis Berlinguette
Intended Audience: 
Graduate

The physical properties of inorganic crystalline materials can be dramatically transformed by controlled introduction of impurities or other defects, without which most semiconductor technologies including transistors, diodes, and solar cells would not be possible. The development and characterization of high-quality doped inorganic crystals has consequently been a perennial research frontier. This talk will describe some of our group's recent research into the development and characterization of doped semiconductor quantum dots as new forms of matter at this research frontier.

What can defect bound states tell us? A case study of superconducting LiFeAs

Speaker: 
Shun Chi, Department of Physics & Astronomy, UBC
Event Date and Time: 
Mon, 2017-02-06 13:00 - 14:00
Location: 
AMPEL 311
Local Contact: 
Doug Bonn
Intended Audience: 
Graduate

What can defect bound states tell us? A case study of superconducting LiFeAs

Electronic Structure of Metal Halide Perovskite Surfaces and Interfaces

Speaker: 
Antoine Kahn, Princeton University
Event Date and Time: 
Thu, 2017-01-19 14:00 - 15:00
Location: 
Hennings 318
Local Contact: 
Sarah Burke

The formidable promises of a recently “re-discovered” class of semiconductors, i.e. the organic/inorganic halide perovskites (HOIP) such as methylamonium lead tri-iodide (MAPbI3), and the rapid and steady rise in device performance achieved with these materials over the past six years, have triggered a flurry of research all over the world. This talk reviews our efforts to understand key interfaces of these materials relevant to optoelectronic devices.

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