Condensed Matter Seminars

Frustrated magnetism in metals

Speaker: 
Eundeok Mun, Department of Physics, Simon Fraser University
Event Date and Time: 
Thu, 2017-11-16 14:00 - 15:00
Location: 
AMPEL #311
Local Contact: 
Josh Folk

To date, magnetic frustration has primarily been studied in insulators. There have been little theoretical and experimental studies in magnetically frustrated conducting materials, where the localized moments reside on geometrically frustrated lattices (pyrochlore, kagome, triangular). For the 4f - electron metallic systems, the competition between Kondo and RKKY interactions results in a great variety of ground states, leading to a rich phase diagram, which can be tuned through a quantum critical point.

Non-fermi liquids, fixed point collisions, and tensorial order in grey tin and in some popular field theories

Speaker: 
Igor Herbut, Simon Fraser University
Event Date and Time: 
Thu, 2017-10-26 14:00 - 15:00
Location: 
AMPEL #311
Local Contact: 
Ian Affleck
Intended Audience: 
Graduate
Abrikosov proposed in 1974 that a 3D electronic system with its fermi level at the point of quadratic band crossing, as in the (spin-orbit coupled) gray tin or mercury telluride, should represent the simplest non-fermi liquid. I will review this idea and discuss how a non-fermi liquid ground state may become unstable to ordering via the mechanism of "fixed-point collision".

Nanophotonic spin-optomechanics

Speaker: 
Paul Barclay, University of Calgary
Event Date and Time: 
Thu, 2017-11-02 14:00 - 15:00
Location: 
AMPEL #311
Local Contact: 
Josh Folk
Intended Audience: 
Graduate

Nano-optomechanical devices enhance the interaction between light and nanomechanical resonators, enabling coherent coupling between photons and mesoscopic phonons. When spin systems are attached to or embedded within these devices, technologies for nanoscale sensing, and for transducing quantum information between photons, phonons and spins become viable. In this talk I will illustrate this potential by presenting measurements of the susceptibility of nanomagnetic spin systems using optomechanical “split-beam” nanocavities [1].

Complex tensor order and quantum criticality in half-Heusler superconductors

Speaker: 
Igor Boettcher, Department of Physics, Simon Fraser University
Event Date and Time: 
Thu, 2017-11-23 14:00 - 15:00
Location: 
AMPEL #311
Local Contact: 
Josh Folk

A revolutionary new direction in the field of superconductivity emerged recently with the synthesis of superconductors with strong inherent spin-orbit coupling of electrons, such as the half-Heusler compounds YPtBi or LuPdBi. Due to band inversion, the low-energy degrees of freedom are electrons at a three-dimensional quadratic band touching point with an effective spin-3/2, which allows for Cooper pairs with spins ranging from 0 to 3.

Collapse of high-Tc superconductivity via ultrafast quenching of the phase coherence

Speaker: 
Fabio Boschini, SBQMI, UBC
Event Date and Time: 
Thu, 2017-10-19 14:00 - 15:00
Location: 
AMPEL #311
Local Contact: 
Andrea Damascelli
Intended Audience: 
Graduate

One of the most fascinating properties of low-density condensates is the emergence of phase transitions driven solely by the fragility of the phase coherence. This intriguing physics has triggered an intense search for tools to control the rigidity of superconducting phases and investigate the collapse of superconductivity induced by phase fluctuations. Electrically-gated oxide interfaces, ultracold Fermi atoms and cuprate superconductors, which are characterized by an intrinsically small phase-stiffness, are paradigmatic examples.

Quantum High Performance Computing for Chemistry and Materials

Speaker: 
Matthias Troyer, Quantum Architectures and Computation Group, Microsoft Research
Event Date and Time: 
Thu, 2017-10-12 14:00 - 15:00
Location: 
AMPEL #311
Following experimental realizations of small but scalable quantum computers we may soon see the first quantum computers with the potential to outperform the fastest classical computers. It is thus timely to identify application problems that a quantum computer could solve better than any classical supercomputer. Despite the challenges posed by mature classical computing technology we can identify several interesting application areas for quantum computers that can make the efforts to build a quantum computer not only a scientifically but also a commercially interesting endeavor.

Signatures of the chiral anomaly in phonon dynamics

Speaker: 
Pedro Lopes, Universite de Sherbrooke
Event Date and Time: 
Thu, 2017-09-28 14:00 - 15:00
Location: 
Hennings 318
Local Contact: 
Ian Affleck

The past decade developments of condensed matter physics research have put a great weight in the importance of topological phenomena. Starting with topological insulators and superconductors new concepts and phase emerged; our particular interest here are Weyl semi-metals.

Exploring the wave physics of mesoscopic materials with ultrasound: from bubble metamaterials to mesoglasses

Speaker: 
John H. Page, Department of Physics and Astronomy, University of Manitoba
Event Date and Time: 
Thu, 2017-09-21 14:00 - 15:00
Location: 
AMPEL #311
Local Contact: 
Alireza Nojeh

Waves in complex media are often strongly scattered due to mesoscopic heterogeneities, leading to unusual and fascinating phenomena which continue to challenge our basic understanding of wave physics.  Ultrasonic techniques are well suited for investigating such phenomena since complete information about wave propagation (both amplitude and phase, in both time and space) can be measured directly in samples with well controlled internal structures.  After an introduction to some of the general features of ultrasonic wave transport in both ordered and disordered mesoscopic materials (e.g., ph

Interacting Majorana fermions in two dimensions

Speaker: 
Ian Affleck, Stewart Blusson Quantum Matter Institute, UBC
Event Date and Time: 
Thu, 2017-09-14 14:00 - 15:00
Location: 
AMPEL #311

Majorana fermions, whose creation operators are Hermitean, have been proposed and apparently observed in various materials. While only two Majorana fermions are expected to occur in some situations, a whole lattice of them may occur in others, including in a thin film of superconductor on top of a topological insulator in the presence of a magnetic field.  A Majorana fermion is then predicted to occur at the core of each superconducting vortex.

Exact zero modes in frustrated spin chains

Speaker: 
Natalia Chepiga, University of California at Irvine
Event Date and Time: 
Thu, 2017-10-05 14:00 - 15:00
Location: 
AMPEL #311
Local Contact: 
Ian Affleck

We will show that the effective coupling between the spin-1/2 edge states of a spin-1 chain of finite length can be continuously tuned by frustration.

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