Quantum paraelectricity probed by superconducting resonators

Abstract

Superconducting coplanar waveguide (CPW) resonators are powerful and versatile tools used in areas ranging from radiation detection to circuit quantum electrodynamics. Their potential for low intrinsic losses makes them attractive as sensitive probes of electronic properties of bulk materials and thin films. Here we use superconducting MoRe CPW resonators to investigate the high-frequency (up to 0.3 GHz) and low-temperature (down to 3.5 K) permittivity of SrTiO 3 , a nonlinear dielectric on the verge of a ferroelectric transition (quantum paraelectricity). We perform a quantitative analysis of its dielectric properties as a function of external dc bias (up to ±15 V), rf power, and mode number and discuss our results within the framework of the most recent theoretical models. We also discuss the origin of a fatigue effect that reduces the tunability of the dielectric constant of SrTiO 3 , which we relate to the presence of oxygen vacancies.

Bimodal Phase Diagram of the Superfluid Density in LaAlO3/SrTiO3 Revealed by an Interfacial Waveguide Resonator

“…The mode visibility as a function of the temperature and V BG is determined by the proximity to the critical coupling condition and by the damping coming from different sources of losses, with coupling, quasiparticles and dielectric losses being the major ones. Here, the broadening and weakening of the peaks at higher frequencies are in agreement with what is expected from the SrTiO 3 substrate [27].…”

Balanced electron-hole transport in spin-orbit semimetal SrIrO3 heterostructures

“…1(a) and the reduced gating efficiency at high voltages observed in Fig. 1(b) [29,30]. In the Supplemental Material, Sec.…”

50 Ohm Transmission Lines with Extreme Wavelength Compression Based on Superconducting Nanowires on High-Permittivity Substrates

“…However, as the wire width increases, the kinetic inductance decreases, and the extreme permittivity of STO results in macroscale transmission lines with characteristic impedances well below 50 Ω. 20 In order to achieve a 50 Ω characteristic impedance at both nanoscale and macroscale dimensions, we have utilized a thin layer of STO grown epitaxially on a bulk silicon (Si) wafer. 21,22 At nanoscale dimensions, the STO dominates the effective permittivity, but as the transmission line width increases, the contribution of the STO to the effective permittivity decreases.…”