Electro- and elastocaloric effects in ferroelectrics: from comprehensive characterization to multicalorics

• Applicant: Dr. Jörg Rudolph
• Subject Area: Experimental Condensed Matter Physics
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 555830780

Solid state-based cooling devices rely on a strong adiabatic temperature response of caloric materials to external fields. Here, we will comprehensively study the multicaloric electro-elastic effect in ferroelectrics using an extension of our existing infrared setup which provides an unparalleled millikelvin and microsecond resolution. Direct, time-resolved measurements of the multicaloric temperature change DT will be performed for simultaneous modulation of both electric field and mechanical stress by detecting the thermal radiation. Observing simultaneously the dynamics of the multicaloric response Delta T(t), the polarization P(t), and the strain epsilon(t) will provide a unique, comprehensive access to the multicaloric effect. We will identify cross-coupling contributions by analyzing the dynamic multicaloric response at different driving frequencies of electric field and mechanical stress, and by comparing the multicaloric effect to the respective monocaloric effects. Different material systems and sample dimensions from bulk to film samples will be investigated. Additionally, we will study the role of different driving waveforms including even complex field protocols. This approach will uniquely allow for the comprehensive investigation of the multicaloric effect in electro-elastic caloric materials, thus paving the way for optimized multicaloric cooling cycles.

• DFG Programme: Research Grants