Correlated electron materials (CEMs) host a rich variety of condensed matter phases. Vanadium dioxide (VO2) is a prototypical CEM with a temperature-dependent metal-to-insulator (MIT) transition with a concomitant crystal symmetry change. External control of MIT in VO2 - especially without inducing structural changes - has been a long-standing challenge. In this work, we design and synthesize modulation-doped VO2-based thin film heterostructures that closely emulate a textbook example of filling control in a correlated electron insulator. Using a combination of charge transport, hard x-ray photoelectron spectroscopy, and structural characterization, we show that the insulating state can be doped to achieve carrier densities greater than 5x10^21 cm^(-3) without inducing any measurable structural changes. We find that the MIT temperature (T_MIT) continuously decreases with increasing carrier concentration. Remarkably, the insulating state is robust even at doping concentrations as high as ~0.2 e-/vanadium. Finally, our work reveals modulation-doping as a viable method for electronic control of phase transitions in correlated electron oxides with the potential for use in future devices based on electric-field controlled phase transitions.
@article{arxiv.2301.02798,
title = {Modulation-Doping a Correlated Electron Insulator},
author = {Debasish Mondal and Smruti Rekha Mahapatra and Abigail M Derrico and Rajeev Kumar Rai and Jay R Paudel and Christoph Schlueter and Andrei Gloskovskii and Rajdeep Banerjee and Frank M F DeGroot and Dipankar D Sarma and Awadhesh Narayan and Pavan Nukala and Alexander X Gray and Naga Phani B Aetukuri},
journal= {arXiv preprint arXiv:2301.02798},
year = {2023}
}
Comments
Main paper 21 pages, 5 Figures. Supporting Information, 18 Pages,15 SI Figures and 1 SI Section