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 (
)
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