Search for R-Parity Violating Supersymmetry and Long-Lived Particles with the ATLAS Detector

We present the results of two recent searches for physics beyond the Standard Model in pp-collision data with a center-of-mass energy of 7 TeV collected by the ATLAS detector at the Large Hadron Collider. The first analysis searches for heavy particles which decay a significant distance from their production point into a final state containing a high-momentum muon, and is based on a 33 pb^-1 data sample. The second is a search for a heavy neutral particle decaying into an emu final state and is based on 0.87 fb^-1 of data. Both searches are motivated by models of R-partity violating supersymmetry, although alternative new physics interpretations are also considered in both cases.