Extreme asymmetry of Néel domain walls in multilayered films of the dilute magnetic semiconductor (Ga,Mn)(As,P)

Abstract

We report on unconventional perfectly shaped, fully asymmetric $\ensuremath{\sim}{90}^{\ensuremath{\circ}}$ N\'eel domain walls in multilayered films of the diluted ferromagnetic semiconductor (Ga,Mn)(As,P) with a stepwise variation of P doping. Our results contradict micromagnetic calculations, which favor symmetric domain walls due to crystallographic anisotropy and stray field energy. We demonstrate that both the puzzling uniaxial in-plane anisotropy in the tetragonal multilayered film and the asymmetry of the domain walls could result from Dzyaloshinskii-Moriya interactions that are enhanced by the multiple sharp interfaces between the layers and from anisotropic nonrelativistic exchange coupling. Our finding shows that digital variations of composition during the molecular beam epitaxy can be used to tune the anisotropy and chirality of magnetic multilayers.