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

  Yoav Kalcheim  
Technion, Israel institute of Technology

Eti Barazani,1 Chubin Huang,1 Pavel Salev,2 Javier del Valle,3 Ivan K Schulller2 and Yoav Kalcheim1

The electronic and magnetic properties of the prototypical Mott insulator V2O3 are very sensitive to stress, which strongly modulates 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. Using this sensitivity, we access hitherto unexplored regions of the phase diagram of this prototypical Mott insulator and suggest an important correction to its long-standing phase diagram.

By growing V2O3 thin films 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.

Here we focus on results obtained on V2O3 films grown on sapphire substrates cut along the (10-10) 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 insulator (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.

Funding: This work is supported by ISF grant No. 1031/21.

1Department of Material Science and Engineering, Technion -Israel Institute of Technology, Haifa 3200003, Israel

2Department of Quantum Matter Physics, University of Geneva, 1211 Geneva, Switzerland

3Department of Physics and Center for Advanced Nanoscience, University of California-San Diego, La Jolla, California 92093, United States;