Condensed Matter Seminars

Femtosecond broadband ellipsometry and magneto-optics: disentanglement of spin and charge dynamics

Speaker: 
Fabio Boschini, Politecnico di Milano
Event Date and Time: 
Thu, 2014-11-06 14:00 - 15:30
Location: 
Hennings 318
Local Contact: 
Andrea Damascelli
Intended Audience: 
Undergraduate

 

Interplay of disorder, nematicity and magnetism in Fe-based Superconductors

Speaker: 
Peter Hirschfeld, University of Florida
Event Date and Time: 
Thu, 2014-10-02 14:00 - 15:00
Location: 
Hennings 318
Intended Audience: 
Graduate
Impurities can nucleate local magnetic states and give rise to quasi-long-range magnetic order in correlated electron systems. In the Fe-based superconductors, stripe-like (pi,0) order usually prevails in parent compounds, but competes with (pi,pi) antiferromagnetism. I show that in such a situation, unusual emergent defect states (``nematogens") can be created by nonmagnetic impurities which strongly break C4 symmetry and may be responsible for local nematic defect structures observed by STM, as well as for the transport anisotropy observed in these materials.

Crystal symmetry and properties of low dimensional epitaxial oxides; interfaces and superlattices

Speaker: 
Gertjan Koster, University of Twente, MESA+ Institute for Nanotechnology
Event Date and Time: 
Mon, 2014-08-18 11:00 - 12:00
Location: 
AMPEL 311
Local Contact: 
Andrea Damascelli
Intended Audience: 
Graduate

In complex oxide materials the occurrence of ferroelectric, ferromagnetic or other properties are for the most part determined by the detailed oxygen coordination of metal cations. More specifically, in the case of perovskite-type materials ABO3, where A and B are metal cations, by the BO6 octahedral orientations and rotations. At interfaces in epitaxial oxide hetero structures, for example magnetic junctions or capacitive structures, this oxygen sub-lattice is found to be different from its bulk counterpart.

Two-dimensional electron gases at oxide interfaces

Speaker: 
Clayton Jackson, University of California, Santa Barbara
Event Date and Time: 
Thu, 2014-07-17 11:00 - 12:00
Location: 
Hennings 318
Local Contact: 
Andrea Damascelli
Intended Audience: 
Graduate

Two-dimensional electron gases (2DEGs) at interfaces between two insulating oxides have attracted significant attention because they can exhibit unique properties, such as strong electron correlations, magnetism and superconductivity. In this presentation, we will discuss emergent properties at interfaces and quantum wells formed between the Mott insulators SmTiO3 and GdTiO3, and the band insulator SrTiO3. These interfaces exhibit a high-density 2DEG of approximately ½ electron per surface unit cell, providing ~ 3×1014 cm-2 mobile charge per interface.

Accurate variational solution for a hole doped into a CuO2 layer

Speaker: 
Hadi Ebrahimnejad
Event Date and Time: 
Thu, 2014-03-27 14:00 - 15:00
Location: 
Hennings 318
Intended Audience: 
Graduate

Since high-temperature superconductivity in cuprates arises upon doping their CuO2 layers, the first step towards deciphering this phenomenon is a proper understanding of the motion of a hole in this layer. We have devised an efficient variational scheme for calculating the spectral properties of a single doped hole, for a multi-band model that properly accounts for the charge-transfer nature of these materials. We verify our choice of variational space by showing that its increase has little effect on the hole's dispersion.

Fermi Surface Signature of a Quantum Critical Point Near Optimal Doping in a High-Tc Superconductor

Speaker: 
Brad Ramshaw
Event Date and Time: 
Thu, 2014-02-20 14:00 - 15:00
Location: 
Hennings 318
Local Contact: 
Doug Bonn
Intended Audience: 
Graduate

The origin of the strange metal phase in the high-Tc cuprates, widely believed to be the key to understanding high-Tc itself, has remained elusive for a quarter of a century. Still unresolved is whether, in the absence of superconductivity, this phase persists to low temperature over a wide range of doping, or if it instead originates from a quantum-critical point beneath the superconducting dome.

Universality and symmetry of charge ordering phenomena in underdoped cuprates

Speaker: 
Riccardo Comin
Event Date and Time: 
Thu, 2014-02-06 14:00 - 15:00
Location: 
Hennings 318
Local Contact: 
Andrea Damascelli
Intended Audience: 
Graduate

The underdoped cuprate pseudogap, and related “Fermi-arc” phenomenology, are one of the most remarkable phenomena in strongly correlated-electron systems. Despite evidence for various forms of electronic instabilities, a direct link to an underlying ordered phase is still mysterious.

Interplay of spin-orbit effects and electron delocalization in honeycomb iridates

Speaker: 
Kateryna Foyevstova
Event Date and Time: 
Thu, 2014-01-30 14:00 - 15:00
Location: 
Hennings 318
Intended Audience: 
Graduate

Strong relativistic spin-orbit coupling in iridium oxides gives rise to new interesting physical effects, such as spin-orbit coupling induced Mott insulating state and anisotropic spin exchange. In honeycomb iridates, e.g., Na2IrO3, the peculiar topology of the Ir lattice introduces additional complexity. Recently, it has been proposed that Na2IrO3 might be a realization of the exotic Heisenberg-Kitaev spin model featuring a rich variety of quantum phases [Jackeli and Khaliullin, Phys. Rev. Lett. 102, 017205 (2009)].

Snapshots of the retarded electronic interaction with spin-fluctuations in high-temperature superconductors

Speaker: 
Claudio Giannetti (i-Lamp & Università Cattolica, Brescia, Italy)
Event Date and Time: 
Thu, 2014-01-23 14:00 - 15:00
Location: 
Hennings 318
Intended Audience: 
Graduate

One of the pivotal questions in the physics of high-temperature superconductors, that is whether there is any boson mediating the low-energy dynamics of the charge carriers [1, 2].

Emergent quantum phases in the iron pnictides and heavy fermion materials

Speaker: 
Andriy Nevidomskyy (Rice University)
Event Date and Time: 
Thu, 2014-01-09 14:00 - 15:00
Location: 
Hennings 318
Intended Audience: 
Graduate

When interactions between constituent particles become sufficiently strong, quantum systems often display appearance of non-trivial collective excitations and novel phases of matter. I will elaborate this concept of quantum emergence on two examples: the "strange metal" (non-Fermi liquid) phase in heavy fermion materials, and the emergent nematic phase in the iron pnictide family. Intriguingly, unconventional superconductivity emerges in both these classes of materials, despite their seemingly very different nature.

Syndicate content
Website development by Checkmark Media. Designed by Armada.

a place of mind, The University of British Columbia

Faculty of Science
Department of Physics and Astronomy
6224 Agricultural Road
Vancouver, BC V6T 1Z1
Tel 604.822.3853
Fax 604.822.5324

Emergency Procedures | Accessibility | Contact UBC | © Copyright The University of British Columbia