Fabrication and Characterization of SrMnO₃ Membranes

Multiferroic materials exhibiting both ferromagnetism and ferroelectricity show promise as future memory, sensor, and spintronic devices due to the coupling of the electric and magnetic orders. One such material, SrMnO₃ (SMO), achieves a multiferroic ferroelectric-antiferromagnetic state at high strains (>1%). At even higher strains (>4.5%), however, SMO is predicted to undergo a transition into a ferroelectric-ferromagnetic state. This would enable direct manipulation of magnetic polarization through an electric signal, which is critical for low-energy memory devices. Traditional epitaxial methods have so far only achieved strains of 3.8%, well below the predicted ferromagnetic transition, and is itself on the limits of strains possible by that method. As such, observation of the ferromagnetic-ferroelectric state will have to be achieved through other sources of strain. Herein, we report fabrication of high quality SMO membranes, as a first step to achieving the strain required to achieve the ferromagnetic-ferroelectric state. Pulsed laser deposition is used to deposit SMO on top of a template consisting of a sacrificial layer grown on a SrTiO₃ (001) substrate. The sacrificial layer is subsequently dissolved in water, and the membrane transferred onto a polyimide film. XRD, XRR, AFM, and transport measurements were performed before and after membrane fabrication to ensure membrane quality.