The temperature dependence of the quantized voltage steps near the superconducting transition temperature of NbAl-Al Ox Nb overdamped Josephson junctions irradiated at 75 GHz has been studied. These junctions can switch between the hysteretic and nonhysteretic regime either by varying a fabrication parameter or, as shown in the present paper, by changing the junction operating temperature. Due to the high values of JC and VC up to 75 kA cm2 and 0.5 mV at 4.2 K, respectively, and to the moderate temperature dependence of these parameters, the height of the first rf-induced step was larger than 1 mA at T=6-8 K, corresponding to 0.7-0.9T TC on a junction of 5×5 ? m2. The flatness at the nanovolt level of this step demonstrates the feasibility of programable or ac voltage standards operating in a cryocooler setup.
Nb/Al-AlO(x)/Nb overdamped Josephson junctions above 4.2 K for voltage metrology
Sabino Maggi;
2007
Abstract
The temperature dependence of the quantized voltage steps near the superconducting transition temperature of NbAl-Al Ox Nb overdamped Josephson junctions irradiated at 75 GHz has been studied. These junctions can switch between the hysteretic and nonhysteretic regime either by varying a fabrication parameter or, as shown in the present paper, by changing the junction operating temperature. Due to the high values of JC and VC up to 75 kA cm2 and 0.5 mV at 4.2 K, respectively, and to the moderate temperature dependence of these parameters, the height of the first rf-induced step was larger than 1 mA at T=6-8 K, corresponding to 0.7-0.9T TC on a junction of 5×5 ? m2. The flatness at the nanovolt level of this step demonstrates the feasibility of programable or ac voltage standards operating in a cryocooler setup.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
