LaCoste linkage vibration isolators have shown excellent performance for ultra-low frequency vertical vibration isolation. However, such isolators depend on the use of conventional pre-stressed coil springs, which suffer from creep. Here, we show that compressional Euler springs can be configured to create a stable tension unit for use in a LaCoste structure. In a proof of concept experiment, we demonstrate a vertical resonance frequency of 0.15 Hz in an Euler-LaCoste configuration with 200 mm height. The system enables the use of very low creep maraging steel as spring elements to eliminate the creep while minimising spring mass and reducing the effect of parasitic resonances. Larger scale systems with optimized Euler spring boundary conditions should achieve performance suitable for applications on third generation gravitational wave detectors such as the proposed Einstein telescope.

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The impurity paramagnetic ion, [Formula: see text] substitutes Al in the [Formula: see text] single crystal lattice, this results in a [Formula: see text] elongated octahedron, and the resulting measured g-factors satisfy four-fold axes variation condition. The aggregate frequency width of the electron spin resonance with the required minimum level of impurity concentration has been evaluated in this single crystal [Formula: see text] at 20 millikelvin. Measured parallel hyperfine constants, [Formula: see text], were determined to be [Formula: see text] and [Formula: see text] at [Formula: see text] for the nuclear magnetic quantum number [Formula: see text], and [Formula: see text] respectively. The anisotropy of the hyperfine structure reveals the characteristics of the static Jahn-Teller effect. The second-order-anisotropy term, [Formula: see text], is significant and cannot be disregarded, with the local strain dominating over the observed Zeeman-anisotropy-energy difference. The Bohr electron magneton, [Formula: see text], (within [Formula: see text] so-called experimental error) has been found using the measured spin-Hamiltonian parameters. Measured nuclear dipolar hyperfine structure parameter [Formula: see text] shows that the mean inverse third power of the electron distance from the nucleus is [Formula: see text] a.u. for [Formula: see text] ion in the substituted [Formula: see text] ion site assuming nuclear electric quadruple moment [Formula: see text] barn.