Condensed Matter Seminar

Abstract: Lanthanide atoms are promising ingredients for realizing single molecule magnets which remain magnetically stable at elevated temperatures. They are also being explored for their use in quantum information processing due to the relatively long relaxation times and phase coherence times of their magnetic 4f-electrons and nuclear spins. These useful properties arise in part due to the strong localization of their 4f electrons, which are shielded from the surrounding environment by their much larger valence 6s and 5d electrons.

Abstract: Motivated by the recent realization of an artificial quantum spin ice in an array of superconducting qubits with tunable parameters, we scrutinize a quantum six-vertex model on the square lattice that distinguishes type-I and type-II vertices. We map the zero-temperature phase diagram using numerical and analytical methods. Following a symmetry classification, we identify three crystalline phases alongside a subextensive manifold of isolated configurations.

Abstract: Superconducting devices subject to strong charging energy interactions and Coulomb blockade are one of the key elements for the development of nanoelectronics and constitute common building blocks of quantum computation platforms and topological superconducting setups. The study of their transport properties is nontrivial and some of their nonperturbative aspects are hard to capture with the most ordinary techniques. Here we present a matrix product state approach to simulate the real-time dynamics of these systems.

Abstract: Application relevant materials are usually polycrystalline, and one of the major challenges in structural analysis resides in accurately identifying the grain boundary orientation and size distribution over a wide field of view with enough spatial resolution to capture tens-of-nanometer sized domains.

Abstract: In chemistry and biochemistry, chirality represents the structural asymmetry characterized by non-superimposable mirror images for a material like DNA. In physics, however, chirality commonly refers to the spin-momentum locking of a particle or quasiparticle in the momentum space. While seemingly unrelated characters in different fields, the structural chirality leads to the electronic chirality featured by the orbital-momentum locking encoded in the wavefunction of chiral molecules or solids, i.e.

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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.