motion in inhomogeneous films*

In this talk, I will discuss current-driven skyrmion motion in disordered films. There are three phases: pinning phase, disorder-boosted transverse motion, and disordered-suppressed transverse motion. I will focus on the origin of the transverse motion boosting. Random potential landscape generate a force on a skyrmion. The force is perpendicular to the current direction when the skyrmion is pinned. The disorder-induced force is opposite to the skyrmion velocity when it is moving. Under a sufficient high current, disorders below a critical strength can boost the transverse skyrmion motion and hinder the longitudinal motion. The boosting comes mainly from the pinning force that is opposite to the driving force of the current. Skyrmions are pinned under a low current and above the critical disorder strength. Both transverse and longitudinal skyrmion motions are hindered at an intermediate current. The phase diagram will also be discussed.