Research interests
Prof McMahon's research is in the behaviour of materials at extremes of pressure and temperature.

At extreme pressures, where atoms are pushed close together, it was long assumed that all materials would become metallic, with simple, close-packed crystal structures. By investigating the structures of materials under such conditions using synchrotron radiation, McMahon’s research has shown that this is untrue, and that even the simplest of elements adopt wholly unexpected structural complexity at high density. The array of complex and incommensurate structures that has been unveiled are unlike anything seen at ambient conditions. In addition to using synchrotron storage rings, McMahon also uses large laser platforms and x-ray lasers to investigate the behaviour of materials under dynamic compression on femtosecond timescales.