Ferroelectric and ferroionic multifunctional quantum sensors: Incursion into applications

Ferroelectric materials are poised to drive the next technological leap through their emergent functionalities, including negative capacitance and resistance, charge accumulation without transport, and spontaneous polarization switching. The discovery of ferroionic material-systems that combine room-temperature ferroelectricity and fast ionic conductivity has opened an unprecedented avenue for multifunctional devices that merge the territories of electronics and ionics. These hybrid materials enable the direct coupling of ionic and electronic order parameters, allowing long-range electrostatic interactions, wireless field communication, and energy transduction across solid–solid and solid–air interfaces. Such capabilities offer potential solutions to long-standing challenges, including the Boltzmann limit in transistor subthreshold operation, voltage amplification without power dissipation, and nonvolatile polarization states with ionic reconfigurability. Beyond conventional applications, ferroionics support a new generation of quantum sensors and adaptive devices, spanning optical, electrical, mechanical, thermal, and magnetic domains. This review provides a comprehensive overview of the conceptual foundations, theoretical frameworks, and experimental progress underlying ferroionic systems, highlighting their role as a bridge between ferroelectrics, solid electrolytes, and correlated quantum materials. Finally, perspectives are offered on how ferroionic coupling may reshape device physics and enable sustainable, self-powered information and energy technologies.