# Atomically-Smooth Single-Crystalline VO$_2$ thin films with Bulk-like Metal-Insulator Transitions

## TL;DR

This study demonstrates the successful growth of atomically-smooth VO$_2$ thin films with bulk-like metal-insulator transitions using pulsed laser deposition, highlighting the importance of substrate preparation and optimal growth conditions.

## Contribution

It presents a novel method for depositing rutile VO$_2$ films with atomic-layer precision, enabling the study of exotic phases at oxide interfaces.

## Key findings

- VO$_2$ films exhibit a sharp MIT at ~325 K with a 10^3 resistance change.
- Optimal substrate preparation and temperature are crucial for atomically-smooth film growth.
- Films show step-and-terrace structures similar to the substrate.

## Abstract

Atomically-abrupt interfaces in transition metal oxide (TMO) heterostructures could host a variety of exotic condensed matter phases that may not be found in the bulk materials at equilibrium. A critical step in the development of such atomically-sharp interfaces is the deposition of atomically-smooth TMO thin films. Optimized deposition conditions exist for the growth of perovskite oxides. However, the deposition of rutile oxides, such as VO$_2$, with atomic-layer precision has been challenging. In this work, we used pulsed laser deposition (PLD) to grow atomically-smooth VO$_2$ thin films on rutile TiO$_2$ (101) substrates. We show that optimal substrate preparation procedure followed by the deposition of VO$_2$ films at a temperature conducive for step-flow growth mode is essential for achieving atomically-smooth VO$_2$ films. The films deposited at optimal substrate temperatures show a step and terrace structure of the underlying TiO$_2$ substrate. At lower deposition temperatures, there is a transition to a mixed growth mode comprising of island growth and layer-by-layer growth modes. VO$_2$ films deposited at optimal substrate temperatures undergo a metal to insulator transition at a transition temperature of $\sim$325 K with $\sim$10$^3$ times increase in resistance, akin to MIT in bulk VO$_2$.