A high frequency magnetocooling cycle and direct Delta T measurements in ferroic thin films and low volume samples

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We will investigate the adiabatic temperature change Delta T and dissipative heating in magnetocaloric and electrocaloric samples under cyclic field changes. Such measurements are required for identifying high performance materials within the priority programme that will be the basis of future cooling devices with high efficiency. The measurements will be based on our modulation infrared thermometry (MIT) setup, that proved to be capable of detecting Delta T with sub-mK resolution and gave worldwide the first Delta T data on a thin film sample. We want to install a new magnet for operating MIT with magnetic field amplitudes of more than 1~T and frequencies reaching 100~Hz. High fields are required to investigate samples under conditions that mimic a future cooling device. High frequencies allow for the investigation of thin film materials libraries as the determination of the temperature is faster than heat diffusion. Electrocaloric materials (namely highly dielectric relaxor materials) will be investigated regarding their temperature dependent Delta T, their frequency dependent behavior, their dissipative heating, and long time-relaxation behavior (aging) for different measurement protocols. We will continue our activities on a high frequency magnetocaloric cooling devices.