| Abstrakt: |
Herein, the experimental observation of micrometer‐scale magnetic skyrmions at room temperature in several Pt/Co‐based thin film heterostructures designed to possess low exchange stiffness, perpendicular magnetic anisotropy, and a modest interfacial Dzyaloshinskii–Moriya interaction (iDMI) is reported. It is found both experimentally and by micromagnetic and analytic modeling that a low exchange stiffness and modest iDMI eliminates the energetic penalty associated with forming domain walls in thin films. When the domain wall energy density approaches negative values, the remanent morphology transitions from a uniform state to labyrinthine stripes. A low exchange stiffness, indicated by a sub‐400 K Curie temperature, is achieved in Pt/Co, Pt/Co/Ni, and Pt/Co/Ni/Re structures by reducing the Co thickness to the ultrathin limit (<0.3 nm). Similar effects occur in thicker Pt/Co/NixCu1−x structures when the Ni layer is alloyed with Cu. At this transition in domain morphology, skyrmion phases are stabilized by small (<1 mT), perpendicular magnetic fields, and skyrmion motion in response to spin–orbit torque is observed. While the temperature and thickness‐induced morphological phase transitions observed are similar to the well‐studied spin reorientation transition that occurs in the ultrathin limit, the underlying energy balances are substantially modified by the presence of an iDMI. [ABSTRACT FROM AUTHOR] |
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