Strong polaritonic interaction between flux-flow and phonon resonances in Bi2Sr2CaCu2O8+x intrinsic Josephson junctions: Angular dependence and the alignment procedure

Abstract

Bi 2 Sr 2 CaCu 2 O 8+x single crystals represent natural stacks of atomic scale intrinsic Josephson junctions, formed between metallic CuO 2 -Ca-CuO 2 and ionic insulating SrO-2BiO-SrO layers. Electrostriction effect in the insulating layers leads to excitation of c-axis phonons by the ac-Josephson effect. Here we study experimentally the interplay between and velocity matching (Eck) electromagnetic resonances in the flux-flow state of small mesa structures with c-axis optical phonons. A very strong interaction is reported, which leads to formation of phonon-polaritons with infrared and Raman-active transverse optical phonons. A special focus in this work is made on analysis of the angular dependence of the resonances. We describe an accurate sample alignment procedure that prevents intrusion of Abrikosov vortices in fields up to 17 Tesla, which is essential for achieving high-quality resonances at record high frequencies up to 13 THz.

Low anisotropy of the upper critical field in a strongly anisotropic layered cuprateBi2.15Sr1.9CuO6+δ:Evidence for a paramagnetically limited superconductivity

“…At H ab there is a profound Josephson flux-flow phenomenon due to easy sliding of Josephson vortices along the ab-planes [55,60]. This also leads to a positive MR with a peak at H strictly parallel to the ab-planes [61]. The negative c-axis MR persists both in the superconducting [16] and the normal states and is attributed to field suppression of either the superconducting gap ∆ [16] or the pseudogap ∆ P G [29].…”

“…Therefore, at H ab the flux-flow contribution to R ab is small either due to zero Lorentz force or a strong intrinsic pinning in the layered superconductor [65][66][67], which prevents motion of Josephson vortices across the planes. maximum at Θ = 0 • due to onset of the Josephson fluxflow phenomenon [61]. In this case the Lorentz force is directed along the ab-planes and easily drags Josephson vortices with low pinning and viscosity [60].…”

“…maximum at Θ = 0 • due to onset of the Josephson fluxflow phenomenon [61]. In this case the Lorentz force is directed along the ab-planes and easily drags Josephson vortices with low pinning and viscosity [60].…”

Quick and reliable technology for fabrication of stand-alone BSCCO mesas

“…It can be seen that with temperature decreasing the critical current increases and reaches a value of I c = 2.65 mA at T = 30 K. Here and below the critical current value is a current level at which the direct branch exhibits a sharp jump to a higher voltage (V = 3.6 V at 30 K). The critical current density for BSCCO structures is in the range of 10-2000 [17][18][19][20][21][22][23]. In [11] the critical current density along the ab-plane of crystals identical to those used in this work (by size and chemical composition) is investigated and found to be of order…”