Floquet Bessel Tuning of Chern Transport in Altermagnet–Topological-Insulator Interfaces

We propose a mechanically programmable nanoscale Chern valve based on an altermagnet–topologicalinsulator (AM–TI) heterostructure, where thin altermagnetic electrodes impose an anisotropic exchange mass on the surface states of a few-quintuple-layer topological-insulator channel. Periodic strain, delivered for example by integrated piezoelectric or surface-acoustic-wave actuators, modulates the inplane crystalline phase of the altermagnetic order and renormalizes the twofold and fourfold interfacial exchange harmonics through zeroth-order Bessel functions. This amplitude-selective renormalization produces re-entrant Chern plateaus, Hall and thermoelectric polarity inversions, and quantized adiabatic charge pumping with winding number changing from 0 to 2. For representative RuO₂/Bi₂Se₃ parameters, the induced gaps remain in the meV range, while MHz mechanical driving places the system deeply within the adiabatic regime. The predicted signatures are directly accessible in nanoscale Hall-bar geometries through the strain-amplitude dependence of transverse Hall response, gate-tracked thermoelectric Hall response, and the collapse of topological sectors near Bessel zeros. The proposed mechanism therefore provides a low-frequency, on-chip route to mechanically controlled topological transport in nano-spintronic AM–TI devices, without optical Floquet driving or net magnetization reversal.