Navigating Through the Phase Diagram of a Mott Insulator by Substrate-Induced Strain

The electronic and magnetic properties of the prototypical Mott insulator V₂O₃ are very sensitive to stress, which strongly modulate the stability of its various structural, magnetic and electronic phases. In this work we use this sensitivity to manipulate these phases by substrate-induced strain. By growing thin films of V₂O₃ on sapphire substrates of different orientations, we can induce both compressive and tensile stress allowing access to phases which are inaccessible in bulk samples. This kind of manipulation can be useful for developing novel functionalities and tailoring electronic properties for applications such as memory devices, optical switches and neuromorphic hardware.<br/>In this poster I will focus on results obtained on thin films of V₂O₃ grown on sapphire substrates cut along the (100) plane. We find large compressive strain along the c-axis and an expansion perpendicular to it. This anisotropic strain drives V₂O₃ into a regime which has only been shown to be induced by Cr doping, and exhibits multiple transitions as a function of temperature: antiferromagnetic insulating (AFI) → paramagnetic metal (PM) → paramagnetic insulator (PI) → critical point. To track the structural phase transition and the changes in global and local electrical conductivity as a function of temperature, we use a combination of reciprocal space mapping using X-ray diffraction, electrical transport and atomic force microscopy.