  The large integrated luminosity collected by the ATLAS detector at the LHC
provides the opportunity to probe the presence of new physics that could
enhance the rate of very rare processes in the Standard Model (SM). The LHC can
therefore gain considerable sensitivity for flavour changing neutral current
(FCNC) and charged lepton flavour violating (CLFV) interactions of the top
quark. In the SM, FCNCs are highly suppressed while CLFV interactions are
forbidden so any measurable branching ratio for such a process is an indication
of new physics. The production of four top quarks is a rare SM process which
also provides sensitivity to new physics processes. In this contribution, the
latest results of searches for these processes are presented.
