Dynamics and pinning of Josephson vortex lattice in Bi-2212 stacked structures

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Nov 16, 2013 (3 years and 8 months ago)

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Dynamics and pinning of Josephson vortex lattice in Bi
-
2212 stacked
structures


Yu.I. Latyshev
1,
*
,
A.E. Koshelev
2
, L.N. Bulaevskii
3
, M.B. Gaifullin
4
, V.N. Pavlenko
1
,


A.P. Orlov
1
, T. Hatano
4
, T. Yamashita
5


1
Institute of Radio
-
Engineering and Electronic
s RAS, Mokhovaya 11
-
7, 101999 Moscow, Russia

2
Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA

3
Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

4
National Institute for Materials Science, Sengen 1
-
2
-
1,

Tsukuba, 305
-
0047, Japan

5
Hirosaki University, Faculty of Science and Technology, Bunkyo
-
cho 3, Hirosaki, 036
-
8561, Japan



We present our recent studies of Josephson flux
-
flow (JFF) in Bi
-
2212 stacked structures.
These studies cover the following topics:

(1) losses in JFF regime, (2) coherence of JFF, (3)
commensurate pinning of Josephson vortex lattice (JVL) by the stack ends, (4) interaction of
driven JVL with pancake vortex lines, (5) JVL melting. We found that the main contribution
to the dissipation

comes from the quasiparticle (qp) in
-
plane AC currents accompanying JFF.
As shown, that may be used for the extraction of a value and temperature dependence of
quasiparticle in
-
plane conductivity from JFF experiments. The renormalization of Swihart
veloci
ty was found in non
-
linear JFF regime at high JVL speeds when Josephson oscillation
frequency exceeds qp relaxation rate. We demonstrate longitudinal and transversal coherence
of JFF by coherent response to external microwaves of subTHz frequency range. We

found
that microwaves can stabilize the rectangular type of JVL. We discuss the effect of
commensurate pinning of JVL at the ends of mesa that results in oscillations of critical
current on parallel field with periodicity of ½ flux quantum per elementary
junction. We
found the effect of strong negative JFF magneto
-
resistance on small perpendicular
component of field observed at high temperatures. The effect is interpreted as JFF braking by
pancake vortex lines. That appears due to attractive interaction be
tween Josephson vortices
and pancake vortex lines. We discuss also the JVL melting that occurs due to the strong in
-
plane phase fluctuations above Berezinskii
-
Kosterlits
-
Thouless transition temperature.
Experimentally, the JVL melting was determined as the

temperature where commensurate
oscillations of JFF resistance turned to zero. Finally we briefly discuss the conditions for
observation of the THz
-
emission induced by Josephson flux
-
flow.


This work was supported by CRDF Grant No. RP
-
12397
-
MO
-
02 and by th
e Russian Ministry
of Science and Industry Grant No. 40.012.1.111.46.




*

Email: yurilatyshev@yahoo.com