Manganese Deficiency in MnSi Single Crystal and Skyrmion Pinning

The dc magnetization and ac spin susceptibility measurement results of MnxSi single crystals with x ≈ 0.96-1 are reported. Magnetic phase diagrams for Mn
_x
Si of different Mn deficiency levels are mapped and compared. We provide strong evidence that the existence of manganese deficiency is common in the MnSi single crystals due to the high Mn vapor loss during growth, and the Mn deficiencies could be used as pinning centers to stabilize the Skyrmion phase within the magnetic field-temperature phase space.