Nanocalorimetry as a platform for multimodal materials characterization

Orateur : Andreas Rydh (Stockholm University)

In materials research, calorimetry provides basic thermodynamic characterization. Specific heat measurements are sensitive to phase transitions, hysteresis, and effects of fluctuations, and can provide details on critical exponents and order parameters such as those involved in superconductivity, magnetism, and structural transitions/distortions. For a complete understanding of systems with such orders, complementary transport, magnetic, and structural measurements are usually needed. Ideally, such measurements should be performed on one and the same sample in order to avoid spurious effects due to inhomogeneity, history, variations in doping, or differences in absolute temperature or temperature calibration. We have developed a general-purpose, nanocalorimeter for high-resolution specific heat measurements [1]. Through developments in measurement electronics, we have combined our membrane-based nanocalorimeter with concurrent synchrotron x-ray measurements in applied magnetic fields at low temperature [2]. In this setup, the calorimeter acts both as a calorimeter probe and as sample platform, where the sample temperature can be locally controlled and monitored, keeping the cryostat at base temperature. This alleviates beam alignment of small samples and further allows the calorimeter to be used as an in-situ x-ray absorption spectroscopy detector.

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