Supersymmetry (SUSY) is an extension of the Standard Model (SM) that can resolve the gauge hierarchy problem. It can also provide a candidate for Dark Matter (DM). The increase of centre-of-mass energy at the LHC from 8 to 13 TeV greatly extends the mass reach for SUSY searches. Recent results of searches for direct stop pair production, highlighting the zero-lepton channel analysis using 13.3fb-1 of 13 TeV data collected with the ATLAS detector at the LHC, will be discussed. No significant excess is observed over the SM background expectation and exclusion limits are set on the stop and neutralino masses. Limits are also set in terms of simplified models describing the associated production of DM with top quark pairs through a (pseudo)scalar mediator.