Antiferromagnetic spin cycloids imaged with a Scanning Nitrogen-Vacancy Magnetometer

Multiferroics, such as BiFeO₃, in which antiferromagnetism and ferro-electricity coexist at room temperature, appear as a unique platform for spintronic and magnonic devices. The nanoscale structure of its ferroelectric domains has been widely investigated with piezoresponseforce microscopy (PFM) [1,2]. However, the BiFeO₃ nanoscale magnetic textures and their potential for spin-based technology remain concealed. We present two different antiferromagnetic spin textures in BiFeO₃ thin films with different epitaxial strains, measured with a commercial scanning Nitrogen-Vacancy magnetometer (SNVM) [3]. Two BiFeO₃ samples were grown on DyScO₃(110) andSmScO₃(110) substrates. The striped ferroelectric domains in both samples are first observed by the in-plane PFM, and SNVM confirms the existence of the spin cycloid texture. At the local scale, the combination of PFM and SNVM allows to identify the relative orientation of the ferroelectric polarization and cycloid propagation directions on both sides of a domain wall. Our results show the potential for re-configurable nanoscale spin textures on multiferroic systems by strain engineering.

 

[1] Rovillain P., et al. (2010). Electric-field control of spin waves at room temperature in multiferroic BiFeO₃. Nat. Mater. 9, 975–979

[2] Balke N., et al. (2011). Enhanced electric conductivity at ferroelectric vortex cores in BiFeO₃. Nat. Phys. 8, 81–88.

[3] A. Haykal, et al., (2020). Antiferromagnetic textures in BiFeO₃ controlled by strain and electric field. Nat. Commun. 11, 1704.