On the anisotropy of dielectric permittivity in single crystal lanthanum aluminate substrates

The dielectric properties of LaAlO 3 single crystal plates were studied by microwave techniques in a frequency range from 20 to 28 GHz. The measurements were performed using a resonator representing crossed round (cylindrical) and radial evanescent waveguides with the polarization-degenerate fundamental oscillation mode. Various single crystal samples, including those obtained from different manufacturers, exhibit anisotropy in the (100) crystal plane, whereby the permittivity varies within Δε=0.1–0.9.