Mechanical losses in low loss materials studied by Cryogenic Resonant Acoustic spectroscopy of bulk materials (CRA spectroscopy)

毫开尔文温度下YIG-GGG异质结构中与波数相关的磁损耗

Wavenumber-dependent magnetic losses in YIG-GGG heterostructures at millikelvin temperatures

本研究通过传播自旋波谱测量4K至26mK下微米厚YIG样品的磁振子输运，发现波数相关耗散源于与GGG衬底的偶极耦合，自旋波传输的温度依赖性源于稀土离子弛豫，为毫开温区磁振子损耗及单磁振子探测研究提供支撑。

High-sensitivity tool for studying phonon related mechanical losses in low loss materials

Fundamental mechanical loss mechanisms exist even in very pure materials, for instance, due to the interactions of excited acoustic waves with thermal phonons. A reduction of these losses in a certain frequency range is desired in high precision instruments like gravitational wave detectors. Systematic analyses of the mechanical losses in those low loss materials are essential for this aim, performed in a highly sensitive experimental set-up. Our novel method of mechanical spectroscopy, cryogenic resonant acoustic spectroscopy of bulk materials (CRA spectroscopy), is well suited to systematica…

Intrinsic Carrier Losses in Tellurium Due to Radiative and Auger Recombinations

Fully microscopic many-body models based on inputs from first principle density functional theory are used to calculate the carrier losses due to radiative- and Auger-recombinations in bulk tellurium. It is shown that Auger processes dominate the losses for carrier densities in the range typical for applications as lasers. The Auger loss depends crucially on the energetic position of the $H_6$ valence bands. At cryogenic temperatures of 50$\,$K (100$\,$K) the Auger coefficient, $C$, varies by about six (three) orders of magnitude within the range of published distances between these bands and …

Temperature coefficients of crystalline-quartz elastic constants over the cryogenic range [4 K, 15 K]

This paper brings out results of a measurement campaign aiming to determine the temperature coefficients of synthetic quartz elastic constants at liquid helium temperature. The method is based on the relationship between the resonance frequencies of a quartz acoustic cavity and the elastic constants of the material. The temperature coefficients of the elastic constants are extracted from experimental frequency-temperature data collected from a set of resonators of various cut angles, because of the anisotropy of quartz, measured on the very useful cryogenic range [4 K - 15 K]. The knowledge of…