Epitaxial strain tuning of Er3+ in ferroelectric thin films

Abstract

Er 3 + color centers are promising candidates for quantum science and technology due to their long electron and nuclear spin coherence times, as well as their desirable emission wavelength. By selecting host materials with suitable, controllable properties, we introduce new parameters that can be used to tailor the Er3+ emission spectrum. PbTiO3 is a well-studied ferroelectric material with known methods of engineering different domain configurations through epitaxial strain. By distorting the structure of Er3+-doped PbTiO3 thin films, we can manipulate the crystal fields around the Er3+ dopant. This is resolved through changes in the Er3+ resonant fluorescence spectra, tying the optical properties of the defect directly to the domain configurations of the ferroelectic matrix. Additionally, we are able to resolve a second set of peaks for films with in-plane ferroelectric polarization. We hypothesize these results to be due to either the Er3+ substituting different sites of the PbTiO3 crystal, differences in charges between the Er3+ dopant and the original substituent ion, or selection rules. Systematically studying the relationship between the Er3+ emission and the epitaxial strain of the ferroelectric matrix lays the pathway for future optical studies of spin manipulation by altering ferroelectric order parameters.