Janus solutions in M-theory

We present a one-parameter deformation of the AdS_{4} x S^{7} vacuum, which is a regular solution in M-theory, invariant under SO(2,2) x SO(4) x SO(4), and which preserves 16 supersymmetries. The solution corresponds to a holographic realization of a Janus-like interface/defect theory, despite the absence of a dilaton in M-theory. The 2+1-dimensional CFT dual results from the maximally symmetric CFT through the insertion of a dimension 2 operator which is localized along a 1+1-dimensional linear interface/defect, thereby partially breaking the superconformal symmetry. The solution admits a regular ABJM reduction to a quotient solution which is invariant under SO(2,2) x SO(4) x U(1)^2, preserves 12 supersymmetries, and provides a Janus-like interface/defect solution in ABJM theory.