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TT: Fachverband Tiefe Temperaturen

TT 60: Cryotechnique: Refrigeration and Thermometry

TT 60.5: Vortrag

Donnerstag, 19. März 2020, 16:00–16:15, HSZ 103

A Microcalorimeter Based on Metallic Paramagnetic Temperature Sensors — •Matthew Herbst, Andreas Reifenberger, Clemens Velte, Sebastian Kempf, Loredana Gastaldo, Andreas Fleischmann, and Christian Enss — Kirchhoff Institute for Physics, Heidelberg, Germany

We present a micro-fabricated platform designed to measure the heat capacity of mg-sized samples at temperatures between 10 mK and 500 mK. The set-up makes use of the relaxation method, where the thermal response following a well defined heat pulse is monitored in order to extract the specific heat. Thermometry is based on a paramagnetic Ag:Er temperature sensor, which is read out by a dc-SQUID via a superconducting flux transformer. This allows us to reach a relative temperature precision better than 30 nK/√Hz and an addenda heat capacity of 400 pJ/K (at 50 mK). Besides the performance of the set-up, we also present the results of first measurements of holmium-doped noble metals. In conjunction with data obtained from other calorimetric set-ups, we are able to shed light on the complex dynamics of these materials, and precisely determine their specific heat at different temperatures and chemical compositions. The measurements also have direct application for projects such as the neutrino mass experiment ECHo, where the heat capacity of holmium alloys directly influences the energy resolution of the detector.