Spin-Orbit Torque Switching on Miscut Sapphire Without Magnetic Field

The patent applies asymmetry by using a miscut sapphire substrate with a specific crystallographic orientation (e.g., r-plane or c-plane with intentional miscut) to break the in-plane rotational symmetry. This symmetry breaking creates an easy axis of magnetization without requiring an external in-plane magnetic field, thus enabling magnetic field-free switching while simplifying device integration. The asymmetric substrate structure inherently provides the necessary magnetic anisotropy that would otherwise require complex magnetic field control circuits.

The patent utilizes parameter changes by carefully controlling the substrate miscut angle (e.g., 45 degrees for r-plane, 0 degrees for c-plane) and crystallographic orientation during substrate selection and fabrication. By precisely setting these geometric parameters, the substrate inherently provides the desired symmetry breaking and magnetic anisotropy. This approach transforms the manufacturing challenge into a controlled parameter specification, where standard semiconductor fabrication processes can achieve the required precision through established substrate preparation techniques.