Spectral signatures of charge density wave reorientation in ErTe₃ under continuously tunable uniaxial strain

The rare-earth tritelluride family has long been of interest due to their quasi-two-dimensional structure hosting either one or two unidirectional charge density orders dependent on choice of rare-earth element. ErTe₃ hosts two incommensurte and orthogonal charge density wave (CDW) transitions within an orthorhombic lattice where the lattice parameters a and c are extremely close. Transport and diffraction measurements suggest that uniaxial strain reorients the high-temperature CDW order and promotes an emergent tetragonality. Using angle-resolved photoemission spectroscopy on an in-situ continuously tunable uniaxial strain platform, we observe pronounced spectral signatures of CDW reorientation in bulk single crystal ErTe₃. We discuss how strain influences the distribution of CDW domains and the associated electronic gap within a single domain. Our observations achieve remarkable strain-tunable control in ARPES spetra and highlight the rich interplay of phases in systems of non-symmetry enforced degeneracy.