arXiv subjects

Juan I. Aranzadi

Publications and source records attributed to Juan I. Aranzadi.

3 recordsLinked to original sources

arXiv2026

Orbital-angular-momentum control of localized Floquet states and photocurrents in Weyl semimetals

Structured light provides a route to controlling quantum materials not only through its polarization, but also through its spatial profile and orbital angular momentum (OAM). We develop real space theories of a Weyl semimetal driven by a vortex beam and show that optical OAM generates highly localized Floquet vortex states with pronounced circulating photocurrents. Exploiting cylindrical symmetry, we derive a Bogoliubov-de Gennes-like radial equation that resolves the states by angular momentum and reveals their evolution between the light-dressed Weyl cones. For Laguerre-Gaussian beams, the spatially varying drive produces strong hybridization between localized vortex states and bulk states. We complement this continuum description with a Wilson-lattice formulation that retains the full two-dimensional spatial structure and enables direct calculation of local photocurrents. Both approaches consistently identify OAM-induced vortex states localized around the beam axis. The lattice calculation further shows that these states support substantially stronger circulating current densities than the more extended surface states, with the largest current densities associated with the most strongly localized, low-angular-momentum vortex modes. Our results establish optical OAM as a tunable control parameter for creating and manipulating localized current-carrying states in Weyl systems and provide a real-space framework for studying photocurrents generated by spatially structured light.

cond-mat.mes-hall↗

arXiv2026

Microscopic mechanism for resonant light-enhanced pair correlations in K$_3$C$_{60}$

Recent experiments on K3C60 revealed a giant enhancement of the light-induced superconducting-like optical response for pump frequencies near 10 THz, with an efficiency roughly two orders of magnitude larger than for off resonant excitation. Here we show that a resonant enhancement of pair correlations arises naturally in a driven purely electronic model of K$_3$C$_{60}$ with ab initio parameters. The underlying mechanism is a symmetry constrained two-photon pathway: the first photon drives the system from the even-parity ground state to an intermediate odd-parity manifold, while the second photon induces a transition to an even-parity excited state with enhanced pair correlations. Larger-cluster calculations show that the corresponding resonance energy is strongly renormalized downward with system size and connectivity, reflecting the kinetic-energy gain of delocalized photo-excited doublon-holon configurations. A simplified single-orbital model reproduces this scaling trend and reaches a 14-site fcc cluster, where the resonant peak is pushed to 30 THz, with a trend compatible with a further reduction toward the experimental 10 THz scale in larger systems. Varying the Hubbard coupling strength, we find that the resonance is lowest and the pairing enhancement strongest near intermediate couplings, where doublon-holon excitations are both well defined and mobile. Our results establish a purely electronic mechanism for resonant light-enhanced pair correlations in K$_3$C$_{60}$ and support the interpretation of the experimental 10 THz resonance as optical access to a paired many-body excited state rather than improved metallicity. More broadly, they suggest that related resonant pathways may arise in other intermediate-coupling Hubbard materials.

cond-mat.supr-con↗

arXiv2024

Nonperturbative Nonlinear Transport in a Floquet-Weyl Semimetal

Periodic laser driving, known as Floquet engineering, is a powerful tool to manipulate the properties of quantum materials. Using circularly polarized light, artificial magnetic fields, called Berry curvature, can be created in the photon-dressed Floquet-Bloch states that form. This mechanism, when applied to 3D Dirac and Weyl systems, is predicted to lead to photon-dressed movement of Weyl nodes which should be detectable in the transport sector. The transport response of such a topological light-matter hybrid, however, remains experimentally unknown. Here, we report on the transport properties of the type-II Weyl semimetal T$\mathrm{_d}$-MoTe$_\mathrm{2}$ illuminated by a femtosecond pulse of circularly polarized light. Using an ultrafast optoelectronic device architecture, we observed injection currents and a helicity-dependent anomalous Hall effect whose scaling with laser field strongly deviate from the perturbative laws of nonlinear optics. We show using Floquet theory that this discovery corresponds to the formation of a magnetic Floquet-Weyl semimetal state. Numerical ab initio simulations support this interpretation, indicating that the light-induced motion of the Weyl nodes contributes substantially to the measured transport signals. This work demonstrates the ability to generate large effective magnetic fields ($>$ 30T) with light, which can be used to manipulate the magnetic and topological properties of a range of quantum materials.

cond-mat.mes-hall↗