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Jonas Habel

Publications and source records attributed to Jonas Habel.

2 recordsLinked to original sources

Magnetic Bloch Oscillations in Odd-Wave Magnets and the Nonlinear Edelstein Effect

Bloch oscillations (BOs) are a quantum phenomenon in which electrons subjected to an electric field in a periodic potential exhibit an oscillating current without a net drift. In real conductors, scattering reduces the coherence required for BOs driving the system toward a steady state with a DC current. While previous studies have focused on charge transport, charge carriers also possess spin, raising the question of whether BOs can emerge in magnetic observables. Here, we show that the magnetization of odd-wave magnets can undergo BOs before relaxing to the steady-state Edelstein value, a phenomenon we term $\textit{magnetic}$ BOs. Using analytical and numerical methods, we demonstrate this effect in a minimal one-dimensional model of a p-wave magnet and generalize it to two dimensions. Our analysis further reveals that the Edelstein magnetization is generically nonlinear in the applied electric field. Finally, we argue that magnetic BOs can be detected in materials through higher-harmonic generation in THz sub-cycle lightwave spectroscopy. Magnetic BOs provide a genuine non-equilibrium signature of spin-charge coupling in unconventional magnets.

cond-mat.str-el

Breakdown of Chiral Edge Modes in Topological Magnon Insulators

Topological magnon insulators (TMI) are ordered magnets supporting chiral edge magnon excitations. These edge states are envisioned to serve as topologically protected information channels in low-loss magnonic devices. The standard description of TMI is based on linear spin-wave theory (LSWT), which approximates magnons as free non-interacting particles. However, magnon excitations of TMI are genuinely interacting even at zero temperature, calling into question descriptions based on LSWT alone. Here we perform a detailed non-linear spin-wave analysis to investigate the stability of chiral edge magnons. We identify three general breakdown mechanisms: (1) The edge magnon couples to itself, generating a finite lifetime that can be large enough to lead to a spectral annihilation of the chiral state; (2) The edge magnon hybridizes with the extended bulk magnons and, as a consequence, delocalizes away from the edge; (3) Due to a bulk-magnon mediated edge-to-edge coupling, the chiral magnons at opposite edges hybridize. We argue that, in general, these breakdown mechanisms may invalidate predictions based on LSWT and violate the notion of topological protection. We discuss strategies how the breakdown of chiral edge magnons can be avoided, e.g. via the application of large magnetic fields. Our results highlight a challenge for the realization of chiral edge states in TMI and in other bosonic topological systems without particle number conservation.

cond-mat.str-el