Alternating current Josephson effect in intrinsic Josephson bridges in Tl2Ba2CaCu2O8 thin films

Abstract

We have performed transport measurements on bridges patterned in misaligned thin films of the superconductor Tl2Ba2CaCu2O8. There is a c-axis component of current flow along the bridge, giving rise to hysteretic Josephson-like current–voltage curves. The temperature dependence of the critical current follows the Ambegaokar–Baratoff theory with IcRN up to 26 mV at 4.2 K. Microwave emission from the Josephson junctions near Tc (≈103 K) has been detected using an X-band detector. We show that 700±15 junctions in the bridge are actively oscillating, confirming that the junctions are “intrinsic” junctions formed by adjacent copper oxide planes in the Tl2Ba2CaCu2O8 crystal structure.

Temperature dependence of the bulk energy gap in underdopedBi2Sr2CaCu2O8+δKrasnov1 2009Phys. Rev. B489430View full textAdd to dashboardCite

“…Interlayer tunneling occurs in various layered HTSC compounds, such as Bi-2212 [15,26,27,36,37,38], Bi-2201 [39], Tl-2212 [40,41] YBaCuO [42], and some others [43], as well as in intercalated compounds [44]. ITS was also expanded to non-HTSC layered compounds [45,46].…”

Radiation from Intrinsic Josephson Junctions in Misaligned Tl2Ba2CaCu2O8 Thin Films

“…where l is the length of the bridge, b ≈ 0.5 µm, is the film thickness, α is the misaligned angle, s ≈ 1.2 nm is the thickness of the I layers, and t ≈ 0.3 nm is the thickness of S layers [12]. Using (1) we estimate that there are 827 Josephson junctions in the bridge.…”

“…The inset at the bottom shows the critical current (I c ) and lowest critical current (I r ). From the I c and I r values, the Stewart-McCumber parameter, β c , is estimated to be about 1 [12,18]. The I-V curve and inset on the top show that there are three large jumps (1,2,3), which means that large numbers of junctions switch simultaneously to the resistive states.…”

“…By using wet chemical etching method, Tl-2212 films on the substrate were etched into a 3-µm-wide and 5-µm-long microbridge with a bowtie antenna (see Fig. 1) [12]. Four indium pads are pressed on the films to connect the films and copper leads.…”

An Effective Method for Improving Emissions from Intrinsic Josephson Junction Arrays of Misaligned Tl2Ba2CaCu2O8+δ Thin Films

“…Thus, each pair of adjacent Cu-O layers in the microbridge acts as an intrinsic Josephson junction, and the microbridge forms a serially connected junction array. The number of intrinsic Josephson junctions N in the microbridge can be estimated from the following equation [9]:…”