diamagnetic 

https://doi.org/10.1351/goldbook.D01668
Substances having a negative magnetic susceptibility are diamagnetic. They are repelled out of a magnetic field.
See also: paramagnetic
Source:
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1105 [Terms] [Paper]