We report on measurements of the linewidth ∆f of THz radiation emitted from intrinsic Josephson junction stacks, using a Nb/AlN/NbN integrated receiver for detection. Previous resolution limited measurements indicated that ∆f may be below 1 GHz -much smaller than expected from a purely cavity-induced synchronization. While at low bias we found ∆f to be not smaller than ∼ 500 MHz, at high bias, where a hotspot coexists with regions which are still superconducting, ∆f turned out to be as narrow as 23 MHz. We attribute this to the hotspot acting as a synchronizing element. ∆f decreases with increasing bath temperature, a behavior reminiscent of motional narrowing in NMR or ESR, but hard to explain in standard electrodynamic models of Josephson junctions.
Infrared nonlinear optical (IR-NLO) crystals possessing excellent comprehensive performance are highly desirable, yet their preparation remains extremely challenging. Particularly, inorganic chalcogenides with diamond-like (DL) structures provide a tunable material platform for their structural design and functional control. In this work, a strategy involving the construction of chalcogenides with DL structures using the strong polarizability of metal cations has been put forward; thus, a quaternary Hg-containing metal sulfide HgCuPS 4 has been successfully discovered by the high-temperature solid-state technology. A remarkable structural characteristic of HgCuPS 4 is the three-dimensional (3D) defect DL framework constructed by vertex-sharing alignments of asymmetric building motifs (ABMs). The combination of the unique defect DL structure and the strong polarizability of the Hg 2+ cations enables such compound to achieve phase matchability in the IR range with a high laser-induced damage threshold (4.2 × AgGaS 2 ) and a strong second harmonic generation response (d ij = 6.5 × AgGaS 2 ), the best among the quaternary DL chalcogenides reported so far. Moreover, the detailed local dipole moment calculations and the theoretical results based on the length-gauge formalism elucidate that the very high d ij value of HgCuPS 4 originates from the combined effects of distorted [HgS 4 ], [CuS 4 ], and [PS 4 ] ABMs, that is, the 3D defect DL structure. This discovery can effectively help understand and design other promising defect DL metal chalcogenides toward future high-performing IR-NLO applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.