Aretifism
From wipipedia.org
Aretifism is a sexual attraction to people who are without footwear. Whilst such people are necessarily barefoot (or possibly in stocking soles), the attraction is not to the foot but to its naked vulnerability.
Historical, lack of shoes was associated with submission before authority, and with servants and slaves, and so aretifism is often associated with the D/s aspect of BDSM.