Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session T13: Materials, Physics, and Application in TelecommunicationsIndustry Invited Live Streamed
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Sponsoring Units: FIAP Chair: Ichiro Takeuchi, University of Maryland, College Park Room: McCormick Place W-183A |
Thursday, March 17, 2022 11:30AM - 12:06PM |
T13.00001: First Principles Design of Electronic Materials Invited Speaker: Turan Birol Crystalline materials, for example perovskite transition metal oxides, host a wide range of electronic, magnetic, and structural phases that can be exploited in applications. First principles computational methods such as density functional theory use no experimental fitting parameters, and thus provide a reliable means to both reproduce and predict the properties of crystalline electronic materials. These approaches can also be used to perform thought experiments to elucidate the microscopic mechanisms of macroscopic phenomena, build structure-property relationships, and design new materials with desired properties. In this talk, I am going to present results from our recent work on a wide range of emergent phenomena including charge density wave transitions, metallic "ferroelectricity", and transparent correlated metals. I will also briefly discuss three theoretical tools we use most often: Density Functional Theory (DFT), which is the workhorse of first principles calculations of crystalline materials; Dynamical Mean Field Theory (DMFT), which has recently emerged as a means to perform correlated materials design; and group representation theory, which provide a systematic way to approach the symmetry related properties of materials. |
Thursday, March 17, 2022 12:06PM - 12:42PM |
T13.00002: The first Ruddlesden-Popper with out-of-plane ferroelectricity, a candidate millimeter-wave tunable dielectric Invited Speaker: Matthew R Barone While paraelectric (Ba,Sr)TiO3 films were once used as tunable dielectrics in radio frequency (RF) circuits, dielectric loss above 10 GHz renders (Ba,Sr)TiO3 incompatible with the high frequency future of RF electronics. The related Ruddlesden-Popper titanates—(ATiO3)nAO with A = (Ba,Sr)—have demonstrated low loss up to 100 GHz, but these experiments have used interdigitated capacitors leveraging in-plane dielectric tunability, rather than commercially viable metal-insulator-metal (MIM) capacitors requiring out-of-plane dielectric tunability. To achieve out-of-plane tunability in a Ruddlesden-Popper film, first-principles calculations indicate the concentration of barium and the series member, n, should both be maximized, but synthesizing such films is extremely challenging. Here, we refine existing synthesis techniques to grow the highest n Ruddleden-Popper ever reported (n = 20), containing the highest concentration of barium ever accomplished in a Ruddlesden-Popper (A = Ba0.6Sr0.4). With a firm grasp on the synthesis, we have demonstrated epitaxially strained heterostructures of (ATiO3)nAO dielectric layers with metallic SrRuO3 electrodes. Measurements confirm that such Ruddlesden-Popper films are, in fact, ferroelectric and that the dielectric constant is highly tunable at room temperature. To assess their relevance to the future of tunable dielectrics for GHz electronics, it remains to evaluate the dielectric loss of these new phases at frequencies greater than 10 GHz. |
Thursday, March 17, 2022 12:42PM - 1:18PM |
T13.00003: Polar vortices in microwave electronics Invited Speaker: Florian Bergmann Ferroelectric PbTiO3-SrTiO3 superlattice films form polar vortices under the right lattice periodicity conditions. Theorists predict that there is a peak in the real part of the permittivity versus lattice periodicity when vortices form. Some researchers suggest that this peak is due to a large negative permittivity present in the vortex core. Here, we study complex permittivity of super lattice films versus periodicity as a function of frequency to understand the frequency dependent signatures of vortex formation and how they might be indicative of negative permittivity. Our measurements show the complex permittivity from 70 kHz to 110 GHz both parallel and perpendicular to the vortex core and as a function of bias voltage. If true, such a remarkable property could enable new microwave devices including parametric amplifiers and non-reciprocal devices like circulators. |
Thursday, March 17, 2022 1:18PM - 1:54PM |
T13.00004: A Large Amplitude Fourier Synthesizer Derived from the Optical Frequency Comb Invited Speaker: Christian Long 5G millimeter-wave integrated circuits present new challenges for characterization to optimize energy efficiency and performance. Traditional arbitrary-waveform generation and nonlinear microwave measurement struggle to cover all the millimeter-wave bands becoming available for 5G wireless communications. Optically-derived sources are a potential path to generate arbitrary waveforms up to terahertz frequencies with extremely low noise. In this work, we demonstrate optically-derived continuous-wave signals with fine phase and amplitude control at (24.8, 49.6, 74.4, 99.2) GHz, within or near new 5G bands. Our approach begins with a 1550 nm electro-optic frequency comb that provides synchronized-optical tones across more than a terahertz of bandwidth. A programmable spectral filter applies optical amplitude and phase shifts to individual tones from the optical frequency comb. An on-wafer photodiode then converts this optical signal to large-amplitude millimeter-waves with phase and amplitude control. In this way, we demonstrate electronic phase control in 25 milliradian steps and electronic-amplitude control in 0.1 dB steps and then apply this control to additive waveform synthesis. We demonstrate optically-derived arbitrary repetitive waveform synthesis with 24.8 GHz repetition rate and up to 100 GHz of instantaneous bandwidth. |
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