Hidden phases in homovalent and heterovalent substituted BaTiO3

Ferroelectric materials can exhibit metastable phases when exposed to THz pulses, characterized by a polarization integration capability related to the amplitude and frequency of the pulses. These so-called ``hidden'' phases enable gradual switching of polarization that can be utilized in artificial synapses for nonconventional (neuromorphic) computing machines. In this work, we employ large-scale molecular-dynamics simulation based on an effective Hamiltonian approach, and we report on the discovery of hidden phases in Zr- and Nb-doped barium titanate ($\mathrm{BaTi}{\mathrm{O}}₃$). We investigate the formation and the stability of those phases at different stimuli and temperatures (20 and 200 K). Our results shed light on the compositional dependence of the properties of these phases, demonstrating the potential of lead-free relaxor ferroelectrics for near-room-temperature neuromorphic computing.