Effect of Cleaving Temperature on the Surface and Bulk Fermi Surface of Sr2RuO4 Investigated by High Resolution Angle-Resolved Photoemission

TL;DR

This study systematically examines how cleaving temperature affects the surface and bulk electronic structures of Sr2RuO4 using high-resolution ARPES, revealing that cleaving temperature does not suppress surface states and that aging enhances bulk signals.

Contribution

It demonstrates that cleaving temperature is not crucial for surface band suppression and shows that aging and laser ARPES can enhance bulk band detection in Sr2RuO4.

Findings

Surface Fermi surface remains strong at high cleaving temperatures.

Aging of the surface enhances bulk band signals.

Laser ARPES with VUV improves bulk sensitivity.

Abstract

High resolution angle-resolved photoemission measurements are carried out to systematically investigate the effect of cleaving temperature on the electronic structure and Fermi surface of Sr$_2$RuO$_4$. Different from previous reports that high cleaving temperature can suppress surface Fermi surface, we find that the surface Fermi surface remains obvious and strong in Sr$_2$RuO$_4$ cleaved at high temperature, even at room temperature. This indicates that cleaving temperature is not a key effective factor in suppressing the surface bands. On the other hand, in the aged surface of Sr$_2$RuO$_4$ that is cleaved and held for a long time, the bulk bands can be enhanced. We have also carried out laser ARPES measurements on Sr$_2$RuO$_4$ by using vacuum ultra-violet laser (photon energy at 6.994 eV) and found an obvious enhancement of bulk bands even for samples cleaved at low temperature. These information are important in realizing an effective approach in manipulating and detecting the surface and bulk electronic structure of Sr$_2$RuO$_4$. In particular, the enhancement of bulk sensitivity, together with its super-high instrumental resolution of VUV laser ARPES, will be advantageous in investigating fine electronic structure and superconducting properties of Sr$_2$RuO$_4$ in the future.