Electrodynamics of Josephson Vortex Lattice in Layered Superconductors

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15 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

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Electrodynamics of Josephson Vortex Lattice in Layered
Superconductors



Alexei E. Koshelev

Materials Science Division, Argonne National Laboratory,

Argonne, Illinois 60439



T
he Josephson vortex lattice
(JVL)
in layered superconductors is
formed by the in
-
plane
magnetic field
applied along the layers.
The r
esponse

of this state to the high
-
frequency

c
-
axis
electric field is
a
nontrivial

problem
, because JVL couples c
-
axis and in
-
plane degrees of
freedom
.

The experimental studies
for

BSCCO
-
2212 [1]
,

underdo
ped YBCO
-
123 [2]

and other
high
-
T
c

superconductors

revealed interesting behavior of the frequency and field dependences
of the high
-
frequency
response
. We developed a
comprehensive quantitative theory of
electromagnetic response for the Josephson
-
vortex
-
la
ttice state in layered superconductors with
arbitrary anisotropy and quasiparticle dissipation [
3
].
Computing the oscillating phases, we
found the frequency dependences of
the dynamic dielectric function and
the loss function at
different magnetic fields,

including regions of both dilute and dense
JVLs
.

Similar approach
has been used in Ref. [4]

for the dense lattice
.

The shape of the response is mainly determined
by the c
-
axis and in
-
plane dissipation parameters that are inversely proportional to the
an
isotropy.

The main feature of the
loss function

is the

Josephson
-
plasma
-
resonance
(JPR)
peak.

For superconductors with high anisotropy and low effective dissipation,

such as BSCCO,
our theory
predicts a new feature, satellite peaks at frequencies higher t
han the JPR frequency.
They appear due to the excitation of the plasma modes with the wave vectors set by the lattice
structure
. T
he satellite pattern serves as a definite fingerprint of the latt
ice configuration.
In the

dense
-
lattice limit the
JPR

peak mo
ves to higher frequency and

its intensity decreases, in
agreement with analytical

theory

and experiment [1]
.

However, contrary to Ref. [4], we did not
find a low
-
frequency optically
-
active mode in a homogeneous superconductor.
In the case of

very strong in
-
plane dissipation
,

an additional peak in the loss function

app
ears below the
plasma frequency, in agreement with

experiment

for

underdoped
YBCO
-
123 [2]
. It is caused by
the frequency

dependence of the in
-
plane contribution to losses rather than a definite

mode

of
phase oscillations.


[
1
]

I. Kakeya

et al.
, Phys.

Rev. B
72
, 014540 (2005).

[2]

K. M. Kojima,
et al.
, Phys.
Rev.

Lett.,
89
, 247001 (2002
);
A. D. LaForge,
et al.
,

Phys.

Rev. B
7
6
,
054524
(20
07
).

[
3
]

A. E. Koshelev,
Phys.

Rev. B
7
6
,
054525
(20
07
).

[4
]

T. Koyama
, Phys. Rev. B
68
, 224505 (2003);
J. Phys. Soc. Jpn. 73, 2505 (2004).



keywords
:
Josephson vortex lattice, Josephson Plasma Resonance
,

high
-
frequency
response, loss function
.



Please check one of the two.

Invited Oral Presentation (
x
)

Poster P
resentation (

)