Methods for producing a plug in a wellbore within a downhole environment are provided. The method includes introducing a magnetorheological fluid into the wellbore and exposing the magnetorheological fluid to a magnetic field to form a base plug within the wellbore. The base plug contains a viscoelastic solid derived from the magnetorheological fluid. The method also includes introducing a cement slurry into the wellbore and onto the base plug and forming a cement plug on the base plug from the cement slurry.