Electrocaloric properties of epitaxial strontium titanate films

Abstract

The electrocaloric (EC) response of strontium titanate thin films is computed as a function of misfit strain, temperature, electric field strength, and electrode configuration using a nonlinear thermodynamic theory. For films in a capacitor configuration on compressive substrates, the transition between paraelectric and strain-induced ferroelectric tetragonal phases produces a large adiabatic temperature change, Delta T = 5K, at room temperature for electric field changes Delta E = 1200 kV/cm. For films on tensile substrates, the transition between the paraelectric and strain-induced ferroelectric orthorhombic phases can also be accessed using inter-digitated electrodes (IDEs). The maximum EC response occurs for IDEs with a [110] orientation.