Bilayers of NdCo5/Ni8Fe2 can act as reconfigurable racetracks thanks to the parallel stripe domain configuration present in the hard magnetic material with weak perpendicular anisotropy (NdCo5), and its imprint on the soft magnetic layer (Ni8Fe2). This pattern hosts spin textures with well defined topological charges and establishes paths for their deterministic propagation under the effect of pulsed currents, which has been studied as a function of externally applied fields by using Magnetic Transmission X-ray Microscopy. The experiments show guided vortex/antivortex propagation events within the Ni8Fe2 above a threshold current of 3⋅1011 A/m2. Opposite propagation senses have been observed depending on the topological charge of the spin texture, both in the remnant state and under an applied external field. Micromagnetic simulations of our multilayer reveal that the guiding effect and asymmetric propagation sense are due to the magnetic history of the hard magnetic layer. An exchange-bias-based memory effect acts as a magnetic spring and controls the propagation sense by favoring a specific orientation of the in plane magnetization, leading to a system which behaves as a hard-soft magnetic composite with reconfigurable capabilities for a controlled propagation of magnetic topological textures.
@article{arxiv.2406.01091,
title = {Memory effects on the current induced propagation of spin textures in NdCo$_5$/Ni$_8$Fe$_2$ bilayers},
author = {Victoria Vega Fernández and Alicia Estela Herguedas-Alonso and Javier Hermosa and Lucía Aballe and Andrea Sorrentino and Ricardo Valcarcel and Carlos Quiros and Jose Ignacio Martín and Eva Pereiro and Salvador Ferrer and Aurelio Hierro-Rodríguez and María Vélez},
journal= {arXiv preprint arXiv:2406.01091},
year = {2025}
}