Mu-metal is a type of magnetic shielding material that is often used in electron spectroscopy chambers to minimise external magnetic interference. Electron spectroscopy techniques, such as X-ray photoelectron spectroscopy (XPS) or Auger electron spectroscopy (AES), are highly sensitive to magnetic fields. External magnetic fields can distort the trajectories of electrons, leading to inaccuracies in the measurements and affecting the overall performance of the spectroscopy system.