Spectrum of linear modes in triangular arrays of Josephson junctions

P. Caputo, M. V. Fistul, and A. V. Ustinov

Physikalisches Institut III, Universitaet Erlangen-Nuernberg
Erwin-Rommel-Str. 1, D-91058 Erlangen, Germany

We report on the experimental observation of
resonances in single and double row triangular arrays
in the presence of a magnetic field.
The number of resonances is determined by the number of rows constituting
the array, i.e. it depends on the degree of freedom of the system.
The dependences of the voltage positions of these resonances on the 
magnetic field is compared for different values of the cell inductance 
and different critical current densities.
We have analitically obtained the spectrum of linear modes
for single and double row arrays. In the two row array
the spectrum is determined by the behavior
of the horizontal Josephson junctions and
corresponds to the ribbon or checkerboard state.
The magnetic field dependence of the resonance voltages
is mapped to this spectrum and a good accord between the experiments
and the model is observed.