Dresden 2026 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 22: Superconductivity – Poster I
TT 22.33: Poster
Monday, March 9, 2026, 18:00–20:00, P1
In-situ thermometry of Holmium in LiYF4 crystals with Erbium as a probe — •Julia Latour1,2,3, Cesare Mattiroli2, Matthias Althammer3,1, Nadezhda Kukharchyk3,1,4, and Henrik M. Rønnow2 — 1Technische Universität München — 2École Polytechnique Fédérale de Lausanne — 3Walther-Meißner-Institut für Tieftemperaturforschung — 4Munich Center for Quantum Science and Technology
Measurements of sample temperatures in cryogenic environments are, in most cases, performed using resistance thermometers. Such measurements, however, do not allow for determining the actual temperature inside optical crystals, such as LiYF4, due to thermal boundary resistance and thermal-conductivity mismatches between the sample, mounting plate, and sensor. These limitations can be overcome by employing an in-situ spin-temperature measurement technique based on the analysis of changes in the hyperfine energy-level populations of fast-thermalizing, highly coherent electron spin systems. In this work, we investigate mixed ensembles of Holmium and Erbium ions diluted in a LiYF4 host for in-situ spin thermometry. To this end, we monitored the relative changes in the absorption spectra of LiYF4 with 0.1% and 1% Ho doping and 0.005% Er co-doping in the magnetic fields of 0–5 T over the temperature range of 0.1–1 K. We compare the thermometry results for the lower- and higher-doped samples to estimate the impact of ion-ion interactions. Samples doped with only Holmium and Erbium are similarly probed to serve as temperature references.
Keywords: spin thermometry; rare-earth; Holmium; LiYF4; magnetic resonance