C-axis Josephson plasma resonance observed in Tl_2Ba_2CaCu_2O_8 superconducting thin films by use of terahertz time-domain spectroscopy

Thorsmølle, V. K.; Averitt, R. D.; Maley, M. P.; Bulaevskiǐ, L. N.; Helm, Ch.; Taylor, Antoinette

doi:10.1364/ol.26.001292

Cited by 39 publications

(29 citation statements)

References 10 publications

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“…The parameters of BSCCO at low temperatures are ω p /(2π) = 0. anisotropy γ ≈ 150 and as a consequence higher critical current J c ≈ 3 · 10 4 A/cm 2 and higher plasma frequency, ω p /(2π) ≈ 0.75 THz [46].…”

Section: Equations For the Phase Differencesmentioning

confidence: 99%

Radiation from Flux Flow in Josephson Junction Structures

Bulaevskiǐ

Koshelev

2006

J Supercond

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We derive the radiation power from a single Josephson junction (JJ) and from layered superconductors in the flux-flow regime. For the JJ case we formulate the boundary conditions for the electric and magnetic fields at the edges of the superconducting leads using the Maxwell equations in the dielectric media and find dynamic boundary conditions for the phase difference in JJ which account for the radiation. We derive the fraction of the power fed into JJ transformed into the radiation. In a finite-length JJ this fraction is determined by the dissipation inside JJ and it tends to unity as dissipation vanishes independently of mismatch of the junction and dielectric media impedances. We formulate also the dynamic boundary conditions for the phase difference in intrinsic Josephson junctions in highly anisotropic layered superconductors of the Bi 2 Sr 2 CaCu 2 O 8 type at the boundary with free space. Using these boundary conditions, we solve equations for the phase difference in the linear regime of Josephson oscillations for rectangular and triangular lattices of Josephson vortices. In the case of rectangular lattice for crystals with the thickness along the c-axis much larger than the radiation wavelength we estimate the radiation power per unit length in the direction of magnetic field at the frequency 1 THz as ∼ N µW/cm for Tl 2 Ba 2 CaCu 2 O 8 and ∼ 0.04 N µW/cm for Bi 2 Sr 2 CaCu 2 O 8 . For crystals with thickness smaller than the radiation wavelength we found that the radiation power in the resonance is independent on number of layers and can be estimated at 1 THz as 0.5 W/cm (Tl 2 Ba 2 CaCu 2 O 8 ) and 24 mW/cm (Bi 2 Sr 2 CaCu 2 O 8 ). For rectangular lattice, due to superradiation regime, up to half of power fed into the crystal may be converted into the radiation. In the case of triangular or random lattice in the direction perpendicular to the layers the fraction of power converted into the radiation depends on the dissipation rate and is much lower than for rectangular lattice in the case of high-temperature superconductors with nodes in the gap.

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Section: Equations For the Phase Differencesmentioning

confidence: 99%

Radiation from Flux Flow in Josephson Junction Structures

Bulaevskiǐ

Koshelev

2006

J Supercond

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“…1 The Josephson current flowing along the c axis interacts with the electromagnetic field inside the insulating dielectric layers, producing Josephson plasma waves ͑JPWs͒. [1][2][3][4][5][6][7][8][9][10][11][12] In other words, the layered structure of superconductors favors the propagation of electromagnetic waves. A challenge is to excite 13 and to control 14,15 electromagnetic waves in Bi 2 Sr 2 CaCu 2 O 8+␦ ͑BSCCO͒ samples because of their subterahertz and terahertz frequency range, 11,16 which is still hardly reachable for both electronic and optical devices.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear electrodynamics in layered superconductors

et al. 2008

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We analyze theoretically the effect of a weak nonlinearity on the propagation of Josephson plasma waves in layered superconductors. The nonlinearity originates from the Josephson relation between the current density across superconducting layers and gauge-invariant phase difference of the order parameter. We show that strong nonlinear effects can be observed for electromagnetic waves with frequency slightly above or slightly below the plasma frequency. We study the nonlinear plasma resonance accompanied by the hysteretic dependence of the wave amplitude on the frequency. This hysteresis transforms the continuous terahertz radiation into a series of short electromagnetic high-amplitude pulses. We also consider the propagation of a nonlinear terahertz beam localized in the direction across the superconducting layers. This phenomenon is an analog of the self-focusing effect in nonlinear optics. The nonlinear phenomena in layered superconductors considered here can be potentially useful for the design of a new generation of terahertz devices.

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“…The growth process of Tl-2212, and the experimental setup are discussed in Ref. [7]. All experiments were performed in field-cooled mode.…”

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Dynamic Coupling-decoupling Crossover in the Current-driven Vortex State in Tl<inf>2</inf>Ba<inf>2</inf>CaCu<inf>2</inf>O<inf>8</inf> Probed by the Josephson Plasma Resonance

Thorsmolle¹,

Averitt²,

Shibauchi³

et al. 2007

2007 Conference on Lasers and Electro-Optics (CLEO)

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Employing terahertz time-domain spectroscopy, we have measured the Josephson plasma resonance in Tl 2 Ba 2 CaCu 2 O 8 high-T c thin films, and studied the current-driven coupling-decoupling crossover in the driven vortex lattice.The properties of driven periodic structures subject to quenched disorder, including charge-density waves, Wigner crystals and vortex lattices, have become one of the central issues in the phenomenology of nonequilibrium statistical mechanics [1,2]. In the context of the vortex lattice, Koshelev and Vinokur [2] predicted the driven system to undergo a dynamic phase transition at some threshold current between the fluidlike and crystal-like moving states. In other words, an applied current puts forth a scenario where a pinned vortex lattice flows plastically at first as some vortices are depinned, and then becomes more ordered at higher applied currents as more vortices are depinned, possible forming a moving ordered vortex lattice. Thus, beyond some critical value a dynamic phase transition may occur to a more ordered state, characterized by a change from incoherent to coherent vortex motion. C. J. Olson et al.[3] studied both the in-plane and the longitudinal ordering of pancakes in a current-driven anisotropic superconductor by numerical simulations as a function of temperature and pinning disorder. The authors concluded that a dynamic coupling-decoupling crossover does indeed take place at higher currents and temperatures.For a highly anisotropic superconductor, the vortices are stacks of two-dimensional "pancake" vortices in the CuO 2 layers weakly coupled by Josephson and magnetic interactions [4]. At low temperatures and low magnetic fields the vortex lattice is composed of aligned stacks of pancakes (vortex lines). However, the interactions between pancakes in adjacent layers are very weak and vortex lines are easily destroyed by either thermal fluctuations at high temperatures, or by random pinning. The c-axis correlations (longitudinal ordering) are directly related to the interlayer phase coherence, cos[ϕ n,n+1 (r, B)] . ϕ n,n+1 (r, B) is the phase difference between layer n and n + 1, r is the in-plane coordinate, and B is the magnetic field along the c-axis. When the pancake vortices form straight lines perpendicular to the layers, cos[ϕ n,n+1 (r, B)] = 1. However, when the pancake vortices are misaligned perpendicular to the layers, a nonzero phase difference is induced which results in the reduction of cos[ϕ n,n+1 (r, B)] from unity. The Josephson plasma resonance (JPR) is a Cooper pair charge oscillation mode perpendicular to the CuO 2 planes, and directly proportional to the longitudinal ordering. In the presence of a c-axis magnetic field B, the JPR can be written as [5]Here we investigate the current-driven vortex state in the high-T c superconductor, Tl 2 Ba 2 CaCu 2 O 8 (Tl-2212), measuring the Josephson plasma resonance employing terahertz time-domain spectroscopy in transmission [6]. The growth process of Tl-2212, and the experimental setup are discussed in Ref. [7]....

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C-axis Josephson plasma resonance observed in Tl_2Ba_2CaCu_2O_8 superconducting thin films by use of terahertz time-domain spectroscopy

Cited by 39 publications

References 10 publications

Radiation from Flux Flow in Josephson Junction Structures

Radiation from Flux Flow in Josephson Junction Structures

Nonlinear electrodynamics in layered superconductors

Dynamic Coupling-decoupling Crossover in the Current-driven Vortex State in Tl<inf>2</inf>Ba<inf>2</inf>CaCu<inf>2</inf>O<inf>8</inf> Probed by the Josephson Plasma Resonance

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