# Spin-orbit semimetal SrIrO$_3$ in the two-dimensional limit

## TL;DR

This study explores how ultrathin SrIrO₃ transitions from a semimetal to an insulator as thickness decreases, revealing enhanced spin fluctuations and magnetic order near the critical thickness through experiments and theoretical calculations.

## Contribution

It provides new insights into the thickness-induced electronic and magnetic phase transition in SrIrO₃, combining experimental measurements with density functional theory.

## Key findings

- Transition from semimetal to insulator below 4 unit cells
- Enhanced spin fluctuations near the transition
- Gap opening associated with antiferromagnetic order

## Abstract

We investigate the thickness-dependent electronic structure of ultrathin SrIrO$_3$ and discover a transition from a semimetallic to a correlated insulating state below 4 unit cells. Low-temperature magnetoconductance measurements show that spin fluctuations in the semimetallic state are significantly enhanced while approaching the transition point. The electronic structure is further studied by scanning tunneling spectroscopy, showing that 4 unit cells SrIrO$_3$ is on the verge of a gap opening. Our density functional theory calculations reproduce the critical thickness of the transition and show that the opening of a gap in ultrathin SrIrO$_3$ is accompanied by antiferromagnetic order.