Dynamics of multiple-junction stacked flux-flow oscillators: Comparison between theory and experiment

Superluminal geometrical resonances observed inBi2Sr2CaCu2O8+xKatterwe1, Rydh2, Motzkau3 et al. 2010Phys. Rev. B373640View full textAdd to dashboardCite

“…For artificial low-T c stacked Josephson junctions both velocity splitting 3,4 and coherent amplification of radiation 10 were observed experimentally. However, for IJJs only the slowest out-of-phase Fiske steps have been unambiguously detected.…”

“…2 In thin-film stacks, d λ S , magnetic field is nonlocal and is created cooperatively by the whole stack, leading to inductive coupling of junctions. 3,4 The strongest coupling is achieved in atomic scale intrinsic Josephson junctions (IJJs), naturally formed in Bi 2 Sr 2 CaCu 2 O 8+x (Bi-2212) high-T c superconductors. The lack of Lorentz invariance leads to a number of unusual electrodynamic properties, such as splitting of the dispersion relation of electromagnetic waves, 5 and a possibility of superluminal (faster than the slowest electromagnetic wave velocity) fluxon motion, accompanied by Cherenkovlike radiation.…”

“…The lack of Lorentz invariance leads to a number of unusual electrodynamic properties, such as splitting of the dispersion relation of electromagnetic waves, 5 and a possibility of superluminal (faster than the slowest electromagnetic wave velocity) fluxon motion, accompanied by Cherenkovlike radiation. 2,[6][7][8] The coupling facilitates phase-locking of junctions, which may lead to coherent amplification of the emission power 4,9,10 ∝ N 2 , where N is the number of junctions. IJJs allow easy integration of many strongly coupled stacked junctions.…”

“…The accuracy of expansion is O[(s/λ ab ) 4 + (π/(N + 1)) 4 ]. Here c = 3 × 10 8 m/s is the velocity of light in vacuum,…”

“…The (almost) linear dispersion relation of fluxon phonons makes Fiske steps with a given n (almost) equidistant in voltage both for single 37,38 and stacked 4 junctions. From comparison of Eqs.…”