Condensed Matter Seminar

Abstract: While the possibility of viscous electron flow in solid state systems was originally proposed as early as the 1960s [1], possible experimental realizations have remained elusive until the recent availability of several ultra-high-conductivity materials. However, distinguishing between non-Ohmic ballistic and viscous effects, and understanding their origin, has proved challenging. In the quasi-two-dimensional metal PdCoO₂, the strong and unanticipated effect of Fermi surface anisotropy has added an additional layer of complexity [2].

Abstract: For centuries, we have known that when light propagates through a transparent solid, it can disperse, refract and exhibit nonlinear optical effects. However, until relatively recently, it has been more challenging to experimentally address the corresponding question: what happens to the transparent solid as light propagates through it?

Abstract: Improper phases are characterized by a secondary order parameter setting in as a direct consequence of a primary order. In this talk, we highlight an overlooked mechanism that couples order parameter bilinears to odd-parity order parameters such that the latter emerge as improper orders. To this end, we explore a novel perspective on nonsymmorphic symmetries based on extended symmetry groups in real space. We demonstrate how nonsymmorphic symmetries can generate rather nonintuitive couplings between order parameters.

Abstract: The characterisation of strongly-correlated effects in quantum impurity systems (QIS) is particularly challenging due to the infinite size of the environment and the buildup of long-ranged entanglement in the system. Moving beyond standard (perturbative) transport analysis, we develop a framework based on the Numerical Renormalisation Group (NRG) and Variational Matrix Product States (VMPS) methods to resolve strong correlations in QIS.

Abstract: Twenty years following the groundbreaking discovery of graphene, the realm of two-dimensional materials continues to amaze us with captivating physics. One exciting avenue of exploration lies in understanding how the strongly interacting electrons and topological states give rise to superconductivity. However, measuring the superfluid density of these materials is challenging because their thickness are only a few atomic layers, rendering traditional methods inadequate for this frontier of inquiry.

Abstract: For most of the last century, condensed matter physics has been dominated by the Landau's symmetry breaking theory. In this respect, by lowering the temperature, almost all forms of matter reorganize in order to generate some kind of long-range order (well known examples are given by the liquid-solid transition or the paramagnetic-ferromagnetic one). However, in the recent past, there is a clear evidence for several cases that escape this standard description and keep a disordered nature down to very low temperatures.

Abstract: Landau damping of surface plasmons generates hot electron-hole pairs, which carry an initial energy equal to the plasmon quanta before relaxation. These hot carriers hold the promise for nonthermal pathways for photoelectric conversion and photocatalytic reactions.  Despite decades of experimental and theoretical efforts, the mechanism and the precise role of the plasmonic hot carriers have not been well understood.

Abstract: The advent of noisy intermediate quantum scale (NISQ) devices has sparked rapidly growing interest in non-equilibrium quantum dynamics. An outstanding question in this field is understanding universal properties of equilibrating quantum systems. At late times, relaxation of local densities of conserved quantities dominates the approach towards equilibrium, leading to an emergent hydrodynamic description at late times.

Abstract:

Abstract:  Crystalline graphene multilayers present a rich playground to explore correlated electronic phenomena in an ultra-clean setting, free of the inhomogeneities ubiquitous in their twisted counterparts. For instance, Bernal bilayer graphene (BLG) and rhombohedral trilayer graphene both exhibit several symmetry-broken metallic phases at low temperature, as well as superconductors with different pairing symmetries. Moreover, placing a WSe2 monolayer on BLG was shown to promote Cooper pairing to an extraordinary degree, with an order-of-magnitude enhancement of Tc [1].