Local excitations in magnetic materials are usually highly incoherent, since they dephase very quickly due to mutual interactions. However, there are interesting exceptions to this common lore. Our joint experimental and theoretical study of the random rare-earth magnet LiY1−xTbxF4 [1] reveals that a combination of hyperfine interactions,…

Since the discovery of superconductivity at 80 K in single crystals of La3Ni2O7 at pressures above 14.0 GPa, extensive efforts have been made to understand the properties of the bilayer nickelate system at both ambient and high pressure [1-3]. Density-wave-like orders, structural transition, strange metal behavior, oxygen vacancies,…

Fractals -- objects with non-integer dimensions -- occur in manifold settings and length scales in nature, ranging from snowflakes and lightning strikes to natural coastlines. Much effort has been expended to generate fractals for use in many-body physics. Here, we identify an emergent dynamical fractal in a disorder-free, stoichiometric three…

A striking feature of non-Hermitian systems is the presence of two types of topology. One generalizes Hermitian topological phases, and another is intrinsic to non-Hermitian systems, called line-gap topology and point-gap topology. Whereas the bulk-boundary correspondence is a fundamental principle in the former topology, its role in the latter…

Matan Uzan - "de Haas-van Alphen spectroscopy and magnetic breakdown in moiré graphene"

(Followed by Prof. Berthold Jaeck)

Quantum oscillations(QO) originating from the quantization of the electron cyclotron orbits provide ultrasensitive diagnostics of electron bands and interactions in novel materials. We…

Understanding strongly correlated topological quantum phases has been a longstanding challenge. Moiré materials present a unique opportunity as they allow us to engineer flat topological bands and vary the carrier density throughout entire bands in situ using electrostatic gates. I will open the talk by presenting nanoscale images of…

Many of the topological Weyl semimetals host also a Kagome crystal structure that together result in extremely rich electronic phenomenology. The bulk Weyl nodes and the diverging Berry curvature associated with them give rise to an intricate bulk-boundary correspondence hosting open-contour Fermi-arc modes on certain surfaces. The Kagome…

The fractional quantum anomalous Hall effect (FQAHE), the analog of the fractional quantum Hall effect at zero magnetic field, is predicted to exist in topological flat bands under spontaneous time-reversal-symmetry breaking. The demonstration of FQAHE could lead to non-Abelian anyons which form the basis of topological quantum computation…

Quantum geometry quantifies the momentum space textures of the Bloch wavefunctions and impacts substantially the physics of multiband systems. This is also true for van der Waals semiconductors, which are usually described within a parabolic, effective mass, approximation. In this talk, I will start by a general discussion on quantum geometry,…

Topological superconductivity is a sought-after state of matter, particularly in bulk crystalline materials. UTe2 is a recently-discovered contender for topological superconductivity, but its superconducting order parameter remains a matter of contention. In this talk, I will first present a brief overview of key experimental results on the…

While Laughlin identified the fractional quantum Hall state as a consequence of an “incompressible quantum fluid”, well-described by his model  wavefunction  which exhibits “flux attachment”, no fundamental explanation of the energetics driving “flux attachment” has emerged. A new picture reveals that  a…

Studying non-abelian anyons is exciting due to their unique braiding statistics. The 5/2 quantum Hall state has been long proposed to host such localized quasiparticles in the 2D bulk. Resting on ‘bulk-edge’ correspondence, their gapless edge modes are expected to mirror the topological order of the 5/2 quantum state. Supporting an odd number…

Molecular beam epitaxy (MBE) is an epitaxial process by which we could grow single-crystal thin films, heterostructures, and superlattices with the highest achievable purity. Therefore, MBE is known as one of the most advanced and controllable material synthesis methods. In this talk, I will briefly introduce the MBE growth mechanism and then…

In 1937, Ettore Majorana suggested that a particle, which is its own antiparticle might exist. This triggered the interest of high-energy physicists, but, despite the big efforts, there is no evidence of such a particle [1]. In condensed matter, a quasiparticle with such property can be created, i.e. a Majorana zero mode (MZM). MZMs are non…

Title/Abstract TBA

Abstract: The fermion sign problem tends to stymie exploration of
highly entangled phases of fermions, such as those relevant for heavy
fermion quantum criticality. In this talk, I will present recent
progress in simulating Fermi and non-Fermi liquids in the context of
Kondo lattice systems. One of the new ideas is…

Abstract: We propose an externally imposed superlattice potential as a platform for manipulating topological phases, which has both advantages and disadvantages compared to a moire superlattice. In the first example, we apply the superlattice potential to the 2D surface of a 3D topological insulator. The superlattice potential creates tunable…