F. Rudau, R. Wieland, J. Langer, X. J. Zhou, M. Ji, N. Kinev, L. Y. Hao, Y. Huang, J. Li, P. H. Wu, T. Hatano, V. P. Koshelets, H. B. Wang, D. Koelle, and R. Kleiner
Phys. Rev. Applied 5, 044017 – Published 27 April 2016
https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.5.044017
We use 2D coupled sine-Gordon equations combined with 3D heat diffusion equations to numerically investigate the thermal and electromagnetic properties of a 250×70 μm2 intrinsic Josephson junction stack. The 700 junctions are grouped to 20 segments; we assume that in a segment all junctions behave identically. At large input power, a hot spot forms in the stack. Resonant electromagnetic modes oscillating either along the length [(0, n ) modes] or the width [(m , 0) modes] of the stack or having a more complex structure can be excited both with and without a hot spot. At fixed bath temperature and bias current, several cavity modes can coexist in the absence of a magnetic field. The (1, 0) mode considered to be the most favorable mode for terahertz emission can be stabilized by applying a small magnetic field along the length of the stack. A strong field-induced enhancement of the emission power is also found in experiment for an applied field around 5.9 mT.
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