Collective mode and the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>c</mml:mi></mml:math>-axis critical current of a Josephson-coupled superconductor at high parallel magnetic fields

Ln, Bulaevskii; Domı́nguez, Daniel; Mp, Maley; Ar, Bishop; Bi, Ivlev

doi:10.1103/physrevb.53.14601

Cited by 62 publications

(42 citation statements)

References 25 publications

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“…In general ϕ n depend also on the coordinate z, the direction of the applied magnetic field H 0 , but we will neglect this dependence (straight-vortex approach) assuming that width of the crystal along the z-axis is much larger than the radiation wavelength, k ω w ≫ 1. The derivation of equations for ϕ n (t, x) [37,38,39] is similar to that for a single JJ. Using the Maxwell equations, the expression for the intralayer supercurrents via the phase of the superconducting order parameter inside layers and the Josephson relation for interlayer current one need to exclude all variables describing intralayer currents and electromagnetic fields induced by these currents by expressing them via ϕ n .…”

Section: Radiation In Layered Superconductorsmentioning

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: Radiation In Layered Superconductorsmentioning

confidence: 99%

Radiation from Flux Flow in Josephson Junction Structures

Bulaevskiǐ

Koshelev

2006

J Supercond

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“…The connection between λ s and λ ab is given by λ s = sD/(s + D) 2 λ ab . [43,44] In the presence of dissipations and a power input, the energy oscillates with time according to…”

Section: Lagrangian and Model Equationmentioning

confidence: 99%

Phase dynamics in intrinsic Josephson junctions and their electrodynamics

Lin

2009

Phys. Rev. B

174

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We present a theoretical description of the phase dynamics and its corresponding electrodynamics in a stack of inductively coupled intrinsic Josephson junctions of layered high-Tc superconductors in the absence of an external magnetic field. Depending on the spatial structure of the gauge invariant phase difference, the dynamic state is classified into: state with kink, state without kink, and state with solitons. It is revealed that in the state with phase kink, the plasma is coupled to the cavity and the plasma oscillation is enhanced. In contrast, in the state without kink, the plasma oscillation is weak. It points a way to enhance the radiation of electromagnetic from high-Tc superconductors. We also perform numerical simulations to check the theory and a good agreement is achieved. The radiation pattern of the state with and without kink is calculated, which may serve as a fingerprint of the dynamic state realized by the system. At last, the power radiation of the state with solitons is calculated by simulations. The possible state realized in the recent experiments is discussed in the viewpoint of the theoretical description. The state with kink is important for applications including terahertz generators and amplifiers.

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“…This makes excitation of spin waves ineffective by moving vortex lattice induced by a perpendicular magnetic field. When a magnetic field is applied parallel to the layers (in the ab-plane, along the y-axis), the situation is drastically different, because now Josephson vortices [18,19,20,21,22] are induced. In high fields they form a lattice which is quite regular in the x-direction (parallel to the layers).…”

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“…The distribution of the magnetic field B(r) inside intrinsic Josephson junctions is described by coupled finite-difference differential equations for the phase difference ϕ n and for the magnetic field B n inside the junction n between layers n and n + 1 [20,22]. Accounting for the magnetization M n of ions inside intrinsic Josephson junction n we obtain equations for the dimensionless variables ϕ n , b n = B n 2πλ ab λ c /Φ 0 , m n = M n 2πλ ab λ c /Φ 0 and h n = b n − 4πm n :…”

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Spectroscopy of Magnetic Excitations in Magnetic Superconductors Using Vortex Motion

Bulaevskiǐ

Hruška²,

Maley³

2005

Phys. Rev. Lett.

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In magnetic superconductors a moving vortex lattice is accompanied by an ac magnetic field which leads to the generation of spin waves. At resonance conditions the dynamics of vortices in magnetic superconductors changes drastically, resulting in strong peaks in the dc I-V characteristics at voltages at which the washboard frequency of vortex lattice matches the spin wave frequency ωs(g), where g are the reciprocal vortex lattice vectors. We show that if washboard frequency lies above the magnetic gap, peaks in the I-V characteristics in borocarbides and cuprate layered magnetic superconductors are strong enough to be observed over the background determined by the quasiparticles.The coexistence of magnetism and superconductivity was observed in many crystals, such as RMo 6 S 8 , RRh 4 B 4 , RBa 2 Cu 3 O 7−δ and (R,A)CuO 4−δ (A=Sr, Ce) with the temperatures of magnetic ordering T M much smaller than the superconducting critical temperature T c , and also in borocarbides RT 2 B 2 C and ruthenocuprate RuSr 2 GdCu 2 O 8 with T M of the same order as T c . Here R is the rare earth element, while T=Ni, Ru, Pd, Pt. In such crystals f -electrons of ions R give rise to localized magnetic moments, while conducting electrons exhibit the Cooper pairing. In all these crystals, except HoMo 6 S 8 and ErRh 4 B 4 , magnetic moments order antiferromagnetically below T M . Such magnetic ordering coexists with superconductivity without strong interference because spin density varies on the scale much smaller than the superconducting correlation length and net magnetic moment vanishes, for review see Refs. 1, 2, 3.In this Letter we consider interplay between magnetic and superconducting excitations in magnetic superconductors, particularly interaction between a moving vortex lattice and spin waves via the ac magnetic field induced by moving vortices. The energy transfer from vortices to the magnetic system leads to dissipation which is additional to that caused by quasiparticles. This results in strong current peaks in the dc I-V characteristics at voltages at which the washboard frequency of vortex lattice [4] matches the spin wave frequency ω s (k) and k matches a reciprocal vortex lattice vector g.First we consider slightly anisotropic superconductors, i.e. all systems mentioned above except SmLa 1−x Sr x CuO 4−δ and RuSr 2 GdCu 2 O 8 crystals, and probably also Sm 2−x Ce x CuO 4−δ .The latter are layered superconductors with intrinsic Josephson junctions [5,6,7,8].We assume, for simplicity, a uniaxial crystal structure with the principal axis along z. The dc magnetic field is applied along the z-axis and we assume that the magnetic induction B(r), r = x, y, inside the superconductor corresponds to the ideal Abrikosov square vortex lattice (such a lattice is realized in clean borocarbide crystals in field B c in some field intervals [1]). The sublattice magnetization in the case of antiferromagnetic ordering is assumed to be oriented in the (x, y) plane. The dc transport current with the density j is along the y-axis which, due t...

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Collective mode and thec-axis critical current of a Josephson-coupled superconductor at high parallel magnetic fields

Cited by 62 publications

References 25 publications

Radiation from Flux Flow in Josephson Junction Structures

Radiation from Flux Flow in Josephson Junction Structures

Phase dynamics in intrinsic Josephson junctions and their electrodynamics

Spectroscopy of Magnetic Excitations in Magnetic Superconductors Using Vortex Motion

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