Condensed Matter Physics, 2021, vol. 24, No. 1, 13101
DOI:10.5488/CMP.24.13101
arXiv:2103.15490
Title:
Theoretical study of I-V characteristics in a coupled long Josephson junctions based on magnesium diboride superconductor
Author(s):
 
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S.P. Chimouriya
(Department of Physics, Kathmandu University, Dhulikhel, Kavre, Nepal; Central Department of Physics, Tribhuvan University, Kirtipur,
Kathmandu, Nepal),
 
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B.R. Ghimire
(Central Department of Physics, Tribhuvan University, Kirtipur, Kathmandu, Nepal),
 
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J.H. Kim
(College of Science and Engineering, University of Houston Clear Lake, TX, USA)
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In the present work, the current-voltage (I-V) characteristics in a coupled long Josephson junction based on magnesium diboride are
studied by establishing a system of equations of phase differences of various inter- and intra-band channels starting from the microscopic
Hamiltonian of the junction system and simplifying it through the phenomenological procedures such as action, partition function,
Hubbard-Stratonovich transformation (bosonization), Grassmann integral, saddle-point approximation, Goldstone mode, phase dependent
effective Lagrangian and, finally, Euler-Lagrange equation of motion. The system of equations are solved using finite difference
approximation for which the solution of unperturbed sine-Gordon equation is taken as the initial condition. Neumann boundary condition
is maintained at both the ends so that the fluxon is capable of reflecting from the end of the system. The phase dependent current is
calculated for different tunnel voltage and averaged out over space and time. The current-voltage characteristics are almost linear at
low voltage and non-linear at higher voltage which indicates that the more complicated physical phenomena at this situation may occur.
At some region of the characteristics, there exist a negative resistance which means that the junction system can be used in specific
electronic devices such as oscillators, switches, memories etc. The non-linearity is also sensitive to the layer as well as to the
junction thicknesses. Non-linearity occurs for lower voltage and for higher junction and layer thicknesses.
Key words:
two-gap superconductor, coupled long Josephson junction, Hubbard-Stratonovich transformation, perturbed sine-Gordon equation
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