Fabrication of atomically flat cleavage planes with ultrafast laser scribing

The preparation of extensive, atomically flat surfaces remains a central challenge in modern quantum materials research, as many crystals lack natural cleavage planes suitable for advanced surface-sensitive investigations. Here, we demonstrate that laser scribing guided by an ultrafast laser can be applied to facilitate easy cleavage along a desired crystallographic plane under ultra-high vacuum. The method is validated on two brittle materials, SrTiO₃ and Si. The technique allows precise spatial localization of the cleaving site and produces extensive, uniformly oriented, and atomically flat surfaces, as verified by scanning electron microscopy (SEM) and atomic force microscopy (AFM). When applied to SrTiO₃ , the technique enables angle-resolved photoemission spectroscopy (ARPES) measurements of surface electronic states characteristic of the two-dimensional electron liquid (2DEL) hosted at its bare (100) surface. Moreover, ultrafast laser scribing is significantly faster than focused ion beam (FIB) techniques for preparing cleavable planes, offering a more accessible and efficient approach. Owing to its broad applicability, this method establishes a powerful and general framework to prepare high-quality surfaces for advanced photoemission and microscopic investigations of quantum phenomena.