High-pressure tuning of electrical transport in freestanding iridates across dimensions

Abstract

Flexible control of crystalline dimensionality and pressure is highly desirable for discovering emergent phenomena but has rarely been achieved within a single oxide. Here we develop a high-pressure strategy that enables pressure to be applied to most freestanding oxide thin films. Using this approach, we uncover a pressure-driven semimetal-insulator-metal transition in three-dimensional iridates and a pressure-robust insulating state in the two-dimensional limit. First-principles calculations reveal that the contrasting pressure responses arise from fundamentally different pressure evolutions of the effective electron correlation. While the correlation strength decreases systematically with pressure in two dimensions, it evolves nonmonotonically in three dimensions, first increasing and then decreasing under compression. Our work opens new opportunities to explore dimensionality effects in the pressure response of quantum materials.