TY - JOUR

T1 - Vortex mobility in two-dimensional arrays of small Josephson junctions

AU - Chen, C. D.

AU - Delsing, P.

AU - Haviland, D. B.

AU - Harada, Y.

AU - Claeson, T.

N1 - Funding Information:
From the temperature dependence of the vortex mobility, we find a crossover from quantum creep to thermally assisted hopping at 7"=600 mK for all the measured arrays. This is in good agreement with theory. In the case of thermally assisted hopping we find the effective barrier height to be -0.3Ej. We have used the Swedish Nanometer Facility and we gratefully acknowledge financial support from the Swedish Research Council for Engineering Sciences and the Wallenberg Foundation.

PY - 1994/2/2

Y1 - 1994/2/2

N2 - We have measured the temperature and magnetic field dependencies of the zero bias resistance for several 2D arrays of small aluminum Josephson junctions. The normal state resistances RN of the junctions vary between 2.2 and 7.5 kω whereas the ratio of Josephson coupling energy EJ to the charging energy Ec ranges between 4.3 and 0.6, where Ec= e2 2C, C being the junction capacitance. The vortex mobility is deduced from the frustration (i.e. the number of flux quantum per unit cell) dependence of zero bias resistance. The mobility decreases when the temperature is lowered, resulting in a decrease of resistance. Fitting the data to a simple exponential form, we find the barrier for the vortex hopping to be -aEJ, with a≈0.3. For all arrays, there exists a crossover temperature Tcr which separates the regime of thermally assisted hopping from that of quantum creep of vortices. For our samples, Tcr is close to the theoretically predicted value of ωp 2π, where ωp=(8EJEc) 1 2.

AB - We have measured the temperature and magnetic field dependencies of the zero bias resistance for several 2D arrays of small aluminum Josephson junctions. The normal state resistances RN of the junctions vary between 2.2 and 7.5 kω whereas the ratio of Josephson coupling energy EJ to the charging energy Ec ranges between 4.3 and 0.6, where Ec= e2 2C, C being the junction capacitance. The vortex mobility is deduced from the frustration (i.e. the number of flux quantum per unit cell) dependence of zero bias resistance. The mobility decreases when the temperature is lowered, resulting in a decrease of resistance. Fitting the data to a simple exponential form, we find the barrier for the vortex hopping to be -aEJ, with a≈0.3. For all arrays, there exists a crossover temperature Tcr which separates the regime of thermally assisted hopping from that of quantum creep of vortices. For our samples, Tcr is close to the theoretically predicted value of ωp 2π, where ωp=(8EJEc) 1 2.

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U2 - 10.1016/0921-4526(94)90824-9

DO - 10.1016/0921-4526(94)90824-9

M3 - Article

AN - SCOPUS:0039521431

SN - 0921-4526

VL - 194-196

SP - 989

EP - 990

JO - Physica B: Physics of Condensed Matter

JF - Physica B: Physics of Condensed Matter

IS - PART 1

ER -