Spin-mediated hysteretic switching of unidirectional charge density waves by rotating magnetic fields

Charge density waves are a widespread collective electronic order in quantum materials, furnishing key insights into symmetry breaking and competing phases. However, their dynamic control with external fields remains a significant challenge. Here, we report deterministic and hysteretic switching of unidirectional charge density wave orientation via in-plane magnetic field rotation in magnetic kagome metal GdTi₃Bi₄. Atomically resolved spectroscopy shows two types of 3a₀ × 1a₀ charge density wave domains, Q₁ and Q₂ oriented 60° apart along two distinct crystallographic directions and separated by atomically sharp domain walls. Rotating the magnetic field drives reversible transitions between these charge density wave configurations, exhibiting a robust C₂-symmetric phase diagram with pronounced hysteresis. This hysteretic switching is mediated by a field-dependent reorientation of underlying antiferromagnetic spins, revealing a tunable energy landscape with stable and metastable states and modulates the electronic charge order via spin-lattice coupling. Our findings not only demonstrate the switching of charge density wave configurations by in-plane magnetic field but also reveal the mechanism of coupling between charge density wave and magnetic fields, offering new insights into charge density wave manipulation and versatile platform for developing a spin-mediated multistate spin-charge coupling memory and programmable quantum devices.