Electrodynamics of Josephson Vortex Lattice in Layered Superconductors

actorrattleUrban and Civil

Nov 15, 2013 (3 years and 10 months ago)

106 views

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 (

)