# Can magnetic susceptibility χ be -1?

Is it practically possible that the magnetic susceptibility of a substance is -1?

I thought so as such a substance could completely cancel the magnetic field, but I couldn't find anything as such.

• A superconductor does this: the Meissner effect. – mike stone Feb 22 at 16:28

Superdiamagnetism ($$\chi$$ = -1) is a state that occurs in superconductors.
The distance to which an applied field can penetrate below the surface of a superconductor is the London penetration depth. Inside the superconductor, $$\chi$$ is effectively -1.