Numerical simulations on effect of surface impedance in THz wave emission from intrinsic Josephson junctions

21 April 2010 (Wed) 3:30 pm - 5:00 pm

6F seminar room, SENGEN site

Dr. Yoshihiko Nonomura (野々村禎彦 博士)

Particle Simulation and Thermodynamics Group, CMSC, NIMS (NIMS 計算科学センター 粒子・統計熱力学グループ)

Numerical simulations on effect of surface impedance in THz wave emission from intrinsic Josephson junctions

固有ジョセフソン接合のテラヘルツ波発振における表面インピーダンスの影響の数値シミュレーション

Current-induced emission from intrinsic Josephson junctions such as mesa structure of BSCCO is one of promising candidates of continuous source of the electromagnetic waves with ~1 THz frequency. Recently such emission without external magnetic fields was observed, and theoretical models with the in-phase state or pi-phase-kink states were proposed. My numerical study revealed [1] that the in-phase state is stable only in a limited region f or rather small surface impedance Z<5, and that the pi-phase-kink states are stabilized for most parameter regions. I further studied emission in in-plane magnetic fields [2] and found that there exists a crossover for field profile of emission intensity for Z=50~60. For smaller Z the field profile has a nontrivial peak together with a dynamical phase transition between the pi-phase-kink and in-phase states, while for larger Z the field profile decreases monotonically. Such sharp dependence of the field profile of emission intensity on surface impedance may explain recent controversial experiments.

[1] Y. Nonomura, Phys. Rev. B 80, 140506(R) (2009).

[2] Y. Nonomura, arXiv:1003.4045.

Dr. Yoshitaka Tateyama(館山佳尚)