Paramagnetic susceptibility and permittivity measurements at microwave frequencies in cryogenic sapphire resonators

We present high-resolution measurements of the temperature-dependence of mode frequency for three monocrystalline microwave sapphire dielectric resonators at liquid helium temperatures. In two resonators the susceptibility is independent of frequency and displays a non-Curie law behaviour. This can be interpreted as arising from a van Vleck temperature-independent contribution to the paramagnetic susceptibility of the and ions involved. We also report measurements of the combined dependence of thermal expansion and permittivity on temperature in the range 2 - 20 K and show that this is about 50% larger in all three resonators than the value calculated from the presently accepted thermal expansion coefficient of sapphire.

[1]  D. Blair,et al.  High-resolution measurement of the temperature-dependence of the Q, coupling and resonant frequency of a microwave resonator , 1996 .

[2]  Dominique Cros,et al.  Design of very high Q sapphire resonators , 1996 .

[3]  D. Blair,et al.  Latest results of the U.W.A. cryogenic sapphire oscillator , 1995, Proceedings of the 1995 IEEE International Frequency Control Symposium (49th Annual Symposium).

[4]  David Blair,et al.  Ultra-stable sapphire resonator-oscillator , 1993 .

[5]  David Blair,et al.  Ultra-stable cryogenic sapphire dielectric microwave resonators: mode frequency-temperature compensation by residual paramagnetic impurities , 1992 .

[6]  David Blair,et al.  A high stability microwave oscillator based on a sapphire loaded superconducting cavity , 1989, Proceedings of the 43rd Annual Symposium on Frequency Control.

[7]  David Blair,et al.  Effect of paramagnetic impurities on frequency of sapphire-loaded superconducting cavity resonators , 1988 .

[8]  Larry E. Halliburton,et al.  An Investigation Of Epr Spectra In Ti-Doped Sapphire , 1987, Optics & Photonics.

[9]  R. Bramley,et al.  Electron paramagnetic resonance spectroscopy at zero magnetic field , 1983 .

[10]  G. White,et al.  Thermal expansion of reference materials: tungsten and α−Al2O3 , 1983 .

[11]  Robert Shelby,et al.  The low temperature electrical properties of some anisotropic crystals , 1979 .

[12]  K. Kocharyan,et al.  The zero‐field splitting of the Mo3+ ground state in corundum , 1979 .

[13]  V. Gabrielyan,et al.  EPR and Spin–Lattice Relaxation of Mo3+ Ions in Corundum , 1974 .

[14]  D. Smith,et al.  Optical constants of far infrared materials. 2: crystalline solids. , 1973, Applied optics.

[15]  D. J. Arnold.  Magnetic susceptibilities of titanium and vanadium in corundum structures , 1970 .

[16]  A. R. Smith.  Anisotropic Magnetic Susceptibilities of Vanadium and Titanium Ions in Corundum . , 1970 .

[17]  C. Kuper,et al.  An Introduction to the Theory of Superconductivity , 1969 .

[18]  P. Richards,et al.  Far-Infrared Spectra of Al 2 O 3 Doped with Ti, V, and Cr , 1969 .

[19]  A. Schawlow,et al.  Far Infrared Spectra ofAl2O3:Cr3+andAl2O3:Ti3+ , 1967 .

[20]  D. K. Finnemore,et al.  Superconducting Properties of High-Purity Niobium , 1966 .

[21]  J. Lambe,et al.  HYPERFINE SPECTRUM OF CHROMIUM 53 IN Al$sub 2$O$sub 3$ , 1961 .

[22]  J. V. Vleck,et al.  The theory of electric and magnetic susceptibilities , 1934, The Mathematical Gazette.