Berlin 2015 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 51: Magnetic Shape Memory Alloys (Joint Session with MM)

MA 51.1: Vortrag

Freitag, 20. März 2015, 09:30–09:45, H 0112

A new device for thermography measurements of the adiabatic temperature change — •Lars Helmich, Niclas Teichert, and Andreas Hütten — Center for Spinelectronic Materials and Devices, Physics Department, Bielefeld University, Germany

Phase transitions in Magnetic Shape Memory Alloys involve an adiabatic temperature change which can be observed by means of infrared thermography. These infrared investigations can be challenging for metallic thin-film samples for several reasons: On the one hand these thin films are grown on certain substrates which provide a large heat sink. Therefore the samples need to be lifted-off from the substrates. On the other hand a metallic surface reflects parasitical infrared radiation from the environment. This reflection needs to be suppressed in order to measure the real sample temperature.

We report on a new, versatile setup for the measurement of the adiabatic surface temperature change in magnetocaloric samples. The measurement are performed in vacuum, thus heat losses due to convection can be neglected. Furthermore the sample temperature can be varied. Therefore magnetocaloric properties can be observed as a function of the initial temperature.

A special, custom-developed thin film absorption layer is applied to prevent reflections. Heat losses to this absorption layer can be corrected based a numerical heat-transfer model.