  A magnetic skyrmion observed experimentally in chiral magnets is a
topologically protected spin texture. For their unique properties, such as high
mobility under current drive, skyrmions have huge potential for applications in
next-generation spintronic devices. Defects naturally occurring in magnets have
profound effects on the static and dynamical properties of skyrmions. In this
work, we study the effect of an atomic defect on a skyrmion using the
first-principles calculations within the density functional theory, taking MnSi
as an example. By substituting one site of Mn or Si with different elements, we
can tune the pinning energy. The effects of pinning by an atomic defect can be
understood qualitatively within a phenomenological model.
