Synchronization of Josephson junction superlattice in the presence of magnetic

1
Synchronization of Josephson junction
superlattice in the presence of magnetic

• Workshop Superlattices and TeraHertz Radiation
  (Loughborough 2009)

Marat B. Gaifullin Department of Physics,
Loughborough University, Loughborough, UK
Collaborators S. Savelev, Department of
Physics, Loughborough University, UK K. Hirata,
S. Ooi, T. Mochiku, National Institute for
Materials Science, Superconducting Materials
Center, Japan Yu.I. Latyshev, Institute of
Radio-Engineering and Electronics, Russian
Academy of Sciences, Russia
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Josephson junction superlattice

• ?(0)/h ? 6.5THz,
• ?c ?1Åltlts12Å and ?cltlt ?ab,
• d3Å lt ? 15Å Debye screening length,
• lc/lab ? 300-1000,

SIS junctions are strongly underdamped junctions
R.Kleiner, et.al., PRL 68, 2394 (1992) Oya G. et
al. Japan. J. Appl. Phys. 31 L829 (1992)
3
Simple model for Resistively and Capacitively
Shunted Junctions (RCSJ)
Mc Cumber-Stewart parameter is
where
period of Josephson oscillation at
JJ are strongly underdamped junctions at low
temperatures in zero magnetic field.
up to 2000
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Experiments at fm/wlt fp in zero magnetic field
In intrinsic stack of Bi2Sr2CaCu2O8d
VstN h f/ 2 e N about 10 of all stack
R.Kleiner, et.al., PRL 68, 2394 (1992)
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Experiments at fm/wlt fp in damped resistively
shunted stack in Bi2Sr2CaCu2O8d

• Wang H.B. et al.
• Physica C 362, 108 (2001)

n order of step
Shapiro step for only one junction of the stack
was observed
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Experiments at fm/wgtgt fp in zero magnetic field
in hysteretic state in Bi2Sr2CaCu2O8d
Without DC magnetic field
Shapiro steps were observed one by one in strong
hysteretic state on return current branch
Wang H.B. et al. PRL 87, 107002
(2001) Supercond. Sci. Technol. 15, 90 (2002)
N number junction in stack
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Sample preparation and characterization
Samples Slightly overdoped - cut from bulk of
single crystal Strongly underdoped whickers
Doping was confirmed from R(T), R(H)
measurements Size from 1.2x2mkm2 to
38x4.5mkm2 ( L?lJ to LgtgtlJ ) N60 to 2500,
measured from sample thickness
Yu.I. Latyshev, S.-J. Kim, Yamashita, IEEE T.
Appl. Supercond., 9, 4312 (1999)
Structure was made by FIB two side processing
method
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Microwave experiment
BWO with frequency range 74 136GHz range Max
incident m/w power 35mW. Josephson junction stack
on finline antenna in WR-10 waveguide
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On chip characterization of vortex phase diagram
from I-V measurements
S.Ooi, T.Mochiku, K.Hirata Physica C 378-381, 523
(2002)
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I-V measured for slightly overdoped sample on H-T
phase diagram
Sample 10.5 x 7.8 mm2, N1270, Tc 90.5K,
Jc1100A/cm2
Very hysteretic I-V in zero field
I-V without hysteresis in field
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I-V hysteresis for underdoped sample in zero field
20 x 8.8 mm2, N670, Tc79.8K, Jc910A/cm2
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I-V hysteresis for underdoped sample in c -axis
field
20 x 8.8 mm2, N670, Tc79.8K, Jc910A/cm2
b chances abruptly crossing melting line because
wp has a anomaly
Wandering of pancakes works as a shunts in
every layer of Bi2Sr2CaCu2O8d
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VL to BG by H scan at 55K
Vst approaches to voltage of full stack
sinchronization in BG phase
Trajectory on phase diagram
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VL to VG by T scan at 0.4T
I-V hysteresis disappeared approaching VG phase
Trajectory on phase diagram
Vst approaches to voltage of full stack
sinchronization in VG phase
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Collective Shapiro steps in c-axis magnetic
field, N460
, where Fo - quantum flux n order of step N
number junction in stack
Strongly underdoped sample
N is 100 junctions in stack
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Collective Shapiro step in c-axis magnetic field,
Bessel-like m/w power dependence
Underdoped sample 20 x 8.8 mm2, N670, Tc
79.5K, Jc910A/cm2
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Collective Shapiro step in c-axis magnetic field
N1270
Slightly overdoped sample 10.5 x 7.8 mm2,
N1270, Tc 90.5K, Jc1100A/cm2 N 100
junctions in stack
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Collective Shapiro step in c-axis magnetic field
N2508
Overdoped sample 16 x 9.1 x 3.8 mm3, Tc85.5K,
Jc2130A/cm2
N 100 /- 0.8 junctions in stack. Overheating
limited order of step to n1
M.B.Gaifullin et.al., Physica C 468 (2008)
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Wandering of the pancakes
L.I.Glazman,A.E.Koshelev, PRB 43, 2835
(1991) L.N.Bulaevskii et al., PRL 74, 801
(1995) A. E. Koshelev, Phys. Rev. Lett. 77, 3901
(1996)
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Field dependence Mc Cumber-Stewart parameter
Comparison abrupt change of ltcos?n,n1gt,
crossing of the second peak line and the melting
line
M.B.Gaifullin et al., PRL 84, 2945 (2000)
Y.Matsuda et al., PRL 75, 4512 (1995)
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Summary

• Intrinsic stacked Josephson junctions are
  significantly damped in c-axis magnetic field in
  the vortex liquid state and in the vortex glass
  state.
• Phase locking of radiation in stack with external
  coherent irradiation can be achieved for total
  number of junctions in c-axis magnetic field.
• Microscopically, wandering of pancakes is the
  main factor of the damping enhance and
  synchronization. Pancakes works as a shunts in
  every layer of Bi2Sr2CaCu2O8d
• Effectively, pancakes works as a shunts in
  every layer of Bi2Sr2CaCu2O8d
• Results will be used to design HTSC
  spectral detector of THz radiation