Condensed Matter Seminars

Progress in the Fabrication and Imaging of Scanning Tunneling Microscopy Patterned Dopant Nanostructures in Silicon

Speaker: 
Taylor Stock, London Centre for Nanotechnology, University College London, UK
Event Date and Time: 
Fri, 2017-08-25 14:00 - 15:00
Location: 
AMPEL #311
Local Contact: 
Sarah Burke
Intended Audience: 
Graduate

Device structures consisting of 2D patterned dopant atoms in silicon can be fabricated with near atomic precision using the technique of scanning tunnelling microscopy (STM) hydrogen desorption lithography. These types of devices, such as atomic scale wires and single atom transistors, can exhibit a variety of interesting quantum phenomena due to atomic scale spatial confinement of electrons within the structures. Traditionally, the patterned dopant of choice for this technique has been phosphorus (P).

Spectroscopic-Imaging and Spin-Polarized STM Studies of Superconductivity, Nematicity and Magnetism in 11-Iron Chalcogenide Superconductors

Speaker: 
Dr. Udai Raj Singh, Institute for Nanostructure and Solid State Physics, University of Hamburg
Event Date and Time: 
Thu, 2017-09-07 14:00 - 15:00
Location: 
AMPEL #311
Local Contact: 
Doug Bonn
Intended Audience: 
Graduate
Several years after the discovery of iron-based superconductors, the 11 iron-chalcogenide superconductors have been found to exhibit the simplest crystal structure of the iron-based superconductors consisting of planar iron layers with chalcogenide (Te, Se) anions above and below. The crystal structure provides a well-defined and non-polar cleavage plane between chalcogenide layers without any surface reconstruction [1]. Therefore, they have become most suitable candidates for surface-sensitive scanning tunneling microscopy (STM) measurements.

From manipulating oxide surface to thin film fabrications by Molecular Beam Epitaxy

Speaker: 
Fengmiao Li, UBC
Event Date and Time: 
Fri, 2017-08-04 13:30 - 14:30
Location: 
AMPEL #311
Local Contact: 
George Sawatzky

Molecular Beam Epitaxy (MBE) is a very powerful technique with the capabilities to manipulate material properties with atomic precision and grow very high-quality metastable thin films and heterostructures in which new electronic states have large probabilities to emerge especially for the compounds with strong electron correlations such as the transition-metal and rare-earth oxides.

Atomic construction of two-dimensional materials

Speaker: 
Bruce A. Davidson, Physics Department, Temple University, Philadelphia, USA; Oxide MBE Lab, CNR–IOM/TASC National Laboratory, Trieste, Italy
Event Date and Time: 
Thu, 2017-08-03 10:00 - 11:00
Location: 
AMPEL #311
Local Contact: 
Doug Bonn
Intended Audience: 
Graduate
Moore’s law has helped push the search for electronic materials to the twodimensional
limit, where new physical properties and new device physics are being
discovered. For example, single monolayers of transition–metal dichalcogenides (TMDCs)
can show electronic structure different from their bulk counterparts (e.g.

Low-temperature dynamics in non-linear Luttinger liquids

Speaker: 
Jesko Sirker
Event Date and Time: 
Thu, 2017-07-20 14:00 - 15:00
Location: 
AMPEL 311
Local Contact: 
Ian Affleck
Intended Audience: 
Graduate

We generalize nonlinear Luttinger liquid theory to describe the dynamics of one-dimensional quantum critical systems at low temperatures. Analyzing density-matrix renormalization group results for the spin autocorrelation function in the XXZ chain we provide, in particular, direct evidence for spin diffusion in sharp contrast to the exponential decay in time predicted by conventional Luttinger liquid theory.

Edge states and exact zero modes in topological 1D quantum magnets

Speaker: 
Frédéric Mila, Ecole Polytechnique Fédérale de Lausanne, Switzerland
Event Date and Time: 
Thu, 2017-07-06 14:00 - 15:00
Location: 
AMPEL #311
Local Contact: 
Ian Affleck
Intended Audience: 
Graduate

Motivated by recent STM experiments on chains of Co adatoms that have revealed a series of ground state level crossings as a function of an external magnetic field, and by their possible connection to Majorana edge states, I will discuss the coupling between edge states in two topological phases of 1D quantum magnets, the transverse field Ising model, and the Haldane phase of the spin-1 chain. I will show in particular that, for a fixed length, it is possible to monitor the coupling between the edge states by inducing incommensurate correlations inside the topological phase.

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 Akkermans, The Technion, Israel
Event Date and Time: 
Thu, 2017-08-03 14:00 - 15:00
Location: 
AMPEL #311
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

 

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