Tailoring the chirality of magnetic domain walls by interface engineering.

Abstract

Contacting ferromagnetic films with normal metals changes how magnetic textures respond to electric currents, enabling surprisingly fast domain wall motions and spin texture-dependent propagation direction. These effects are attributed to domain wall chirality induced by the Dzyaloshinskii-Moriya interaction at interfaces, which suggests rich possibilities to influence domain wall dynamics if the Dzyaloshinskii-Moriya interaction can be adjusted. Chiral magnetism was seen in several film structures on appropriately chosen substrates where interfacial spin-orbit-coupling effects are strong. Here we use real-space imaging to visualize chiral domain walls in cobalt/nickel multilayers in contact with platinum and iridium. We show that the Dzyaloshinskii-Moriya interaction can be adjusted to stabilize either left-handed or right-handed Néel walls, or non-chiral Bloch walls by adjusting an interfacial spacer layer between the multilayers and the substrate. Our findings introduce domain wall chirality as a new degree of freedom, which may open up new opportunities for spintronics device designs.