Single-crystal dielectric resonators for low-temperature electronics applications

Abstract

Computed properties of high-factor sapphire, YAG, SrLaAlO 4 , LaAlO 3 , rutile, and quartz dielectric resonators (DR's) operating on whispering-gallery TE 011 and TE 01 modes are presented in this paper. Resonators with a superconducting metal or partly superconducting partly metal shield are considered. For whispering-gallery-mode resonators, dielectric losses determine upper limit for their factors, while for TE 011 -mode resonators, their factors are usually limited by conductor losses. Single-crystal TE 01 -mode resonators would have factors determined by both dielectric and conductor losses, and dominant loss mechanism depends on crystal losses and shield geometry. Geometric factors that allow evaluation of conductor losses of TE 011 -and TE 01 -mode resonators are given for different DR structures.

Ultrasensitive multi-mode ESR probed ferromagnetic two-level system of $Mn^{4+}$ impurity ion in the insulated $MnO_6$ complex of $SrLaAlO_4$ at $20~mK$

“…Field confinement of the WG mode in SrLaAlO 4 crystal allows loss mechanisms to be minimized to achieve a high Q-factor at 20 mK [30][31][32][33] , which is required for an ultrasensitive ESR spectroscopy. Using X-band to Kuband frequency WG multi-mode ESR at this temperature, high precision is achieved in the measurements of the spin-Hamiltonian parameters 34,35 .…”

Dielectric Resonators for the Measurements of the Surface Impedance of Superconducting Films

“…While the ultimate sensitivity is obtained with superconducting cavities [14], this method is definitely not feasible when the sample has to be characterized under a dc magnetic field. In this case, metallic cavities [15] or dielectric resonators in low-indices [16,17,18,19] as well as in whispering gallery modes [20,21,22,23] can be used. Dielectric resonators exhibit increased sensitivity, and more compact dimensions.…”

“…Their advantage resides in the capability of measuring unpatterned thin films, using the so called surface perturbation method [24,25]: the sample substitutes part of a metallic wall, thus contributing to dissipation (resistance) and energy storage (reactance) in the resonator. By measuring the quality factor Q and resonant frequency ν 0 of the resonator [17,18,19,20] one can derive Z s . The materials and the geometry chosen for the practical realization of the resonator, as well as the methods adopted for the determination of Q and ν 0 , affect the sensitivity, the accuracy and the precision of the…”

Rigorous ESR spectroscopy of Fe3+ impurity ion with oxygen vacancy in ferroelectric SrTiO3 crystal at 20 mK

“…Field confinement in SrTiO 3 is very high due to its extremely high permittivity at low temperatures, this allows only the loss mechanisms of the crystal itself to determine the resonator Q-factor [10][11][12][13]. Required high Q-factors can be maintained due to no significant metal cavity or radiation losses, necessary to detect paramagnetic impurity ions of concentration level parts per million (ppm) to parts per billion (ppb) at 20 mK.…”