arXiv subjects

Jonathan Curtis

Publications and source records attributed to Jonathan Curtis.

3 recordsLinked to original sources

arXiv2026

Spatially Resolving the Pre-Thermal Anatomy of a Driven Bosonic Fluid

Understanding how coherently driven quantum many-body systems redistribute energy prior to thermal equilibrium remains a central challenge in many-body physics. Here, we utilize nitrogen-vacancy (NV) magnetometry to perform micron-scale spatial imaging of room-temperature magnon dynamics in a yttrium iron garnet (YIG) thin film. We resolve a hierarchy of discrete parametric scattering events that serve as deterministic stepping stones toward thermalization. By applying a two-tone wave-mixing protocol, we first isolate the elementary four-magnon interaction and extract its coupling strength via the spatial growth of the scattering product. We then drive the system with an intense single-frequency excitation near ferromagnetic resonance, revealing that magnon-magnon interactions trigger a spontaneous, multi-generation scattering cascade. We demonstrate that in each generation, the dominant scattering channels correspond to one of the out-scattered magnons being in the slow magnon regime, reminiscent of the enhancement of optical nonlinearities in slow light systems. We capture this dynamics quantitatively using a near field magnonics framework and extract the cascade order and nonlinear coefficients directly from power-dependent frequency shifts. By revealing the multi-stage dynamical process through which monochromatic injected magnons evolve toward equilibrium, our work establishes spatially resolved magnonics as a powerful platform for visualizing non-equilibrium many-body kinetics.

cond-mat.mes-hall↗

arXiv2024

Twist-induced spin splitting and spin-Hall-like effect in antiferromagnetic bilayers

Momentum-resolved spin-polarized bands are a key ingredient in many proposed spintronic devices, but their existence often relies on lattice commensurability or strong spin-orbit coupling. By a large-scale DFT calculation (up to 4212 atoms), we propose a way to realize strongly spin-polarized bands in the absence of these ingredients by twisting monolayers of van der Waals magnetic semiconductor CrSBr. Furthermore, due to the highly anisotropic electronic transport in this material, the twist-induced electronic transport becomes strongly coupled to the spin transport. We show that an in-plane electric field induces a transverse spin current, manifesting a twist-tunable spin-Hall effect in the absence of spin-orbit coupling. Using highthroughput computations, we also identify 231 other material candidates out of a set of 6000 magnetic two-dimensional materials, which satisfy the necessary conditions to realize this behavior, paving the way to widespread application of twist-tunable spin transport.

cond-mat.mtrl-sci↗

arXiv2023

Multiphoton Spectroscopy of a Dynamical Axion Insulator

The unusual magnetoelectric transport present in Weyl semimetals and 3D topological insula- tors can be compactly understood as manifestations of a background axion field, which itself is determined by the microscopic band structure. In the presence of correlations, an additional axion quasiparticle may emerge as the collective excitations on top of the mean background field. Such modes couple nonlinearly to electric and magnetic fields, giving rise to a dynamical magnetoelectric response. However, unambiguous identification of this collective axion mode is challenging due to its inherent nonlinear dynamics. Here, we propose an all-optical protocol that utilizes a pump-probe setup for verifying and characterizing the transient dynamics of axion fields in three-dimensional insulator systems. In particular, we show that nonlinear Raman processes induce dynamical oscillations of the axion field that depend on the geometry of the incident electromagnetic fields. These oscillations manifest in the polarization and magnetization of the material, hence, can be subsequently measured using time-resolved Kerr rotation spectroscopy. Our results open a pathway towards using multi-photon and quantum pair spectroscopies to identify new correlated phases of quantum matter.

cond-mat.str-el↗