External synchronization Josephson oscillations in intrinsic stack of junctions under microwave irradiation and c-axis magnetic field

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External synchronization Josephson oscillations
in intrinsic stack of junctions under microwave
irradiation and c-axis magnetic field

• I.F. Schegolev Memorial Conference
• (Chernogolovka 2009)

Marat B. Gaifullin Department of Physics,
Loughborough University, Loughborough, UK
Collaborators 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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OUTLINE

• Introduction
• Shapiro step observation in intrinsic stack of
  Josephson junctions
• Damping regions of the vortex phase diagram in
• Bi2Sr2CaCu2O8d
• Shapiro steps observation in stack of up to
• 2500 junctions
• Mechanism of the synchronization by
• c-axis magnetic field
• 6. Conclusion

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Josephson junction superlattice in
Bi2Sr2CaCu2O8d

• ?(0)/h ? 6.5THz,
• ?c ?1Åltlts12Å and ?cltlt ?ab,
• d3Å lt ? 15Å Debye screening length,
• lc/lab ? 100-1500,

SIS junctions are strongly underdamped
R.Kleiner, et.al., PRL 68, 2394 (1992) Oya G. et
al. Japan. J. Appl. Phys. 31 L829 (1992)
Mc Cumber b approaches to 2000
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Hysteretic I-V in zero field
20 x 8.8 mm2, N670, Tc79.8K, Jc910A/cm2
Stacked JJ are strongly underdamped in zero
magnetic field.
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Shapiro steps in zero magnetic field
In intrinsic stack of Bi2Sr2CaCu2O8d
N about 10 of all stack
wm/wlt wp
R.Kleiner, et.al., PRL 68, 2394 (1992)
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Experiments in damped resistively shunted stack
in Bi2Sr2CaCu2O8d
N 1, order of step
Shapiro step for only single junction of the
stack was observed

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

wm/wlt wp
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Experiments at wm/wgtgt wp in zero magnetic field
in hysteretic state in Bi2Sr2CaCu2O8d
Without DC magnetic field
Shapiro steps were observed in strong hysteretic
state on return current branch (one by one
switching )
N number junction in stack
Wang H.B. et al. PRL 87, 107002
(2001) Supercond. Sci. Technol. 15, 90 (2002)
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Collective Shapiro steps on flux flow branch
In strong 2.0T magnetic field parallel to
ab-plane (BgtF0/gs2)
Yu.I.Latyshev, M.B.Gaifullin et al. PRL87,
247007 (2001)
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Simple model for Resistively and Capacitively
Shunted Junctions (RCSJ)
Mc Cumber-Stewart parameter is
where
- period of Josephson oscillation at
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I-V measurements and H-T phase diagram
Very hysteretic I-V in zero field
I-V without hysteresis in field
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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 in the
region wp anomaly
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Characterization of vortex phase diagram by
Josephson plasma resonance
underdoped sample
Abrupt changes of
crossing the phase transition lines
Y.Matsuda, M.B.Gaifullin, et al., PRL 75, 4512
(1995)
M.B.Gaifullin, Y.Matsuda, et al., PRL 84, 2945
(2000)
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On chip characterization of vortex phase diagram
by I-V measurements
S.Ooi, T.Mochiku, K.Hirata Physica C 378-381, 523
(2002)
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From Vortex Liquid to Bragg Glass by H scan at 55K
Vst approaches to voltage of full stack
sinchronization in BG phase
Trajectory on phase diagram
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From Vortex Liquid to Vortex Glass 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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From Vortex Glass to Bragg Glass by H scan at 35K
Slightly overdoped sample 10.5 x 7.8 mm2,
N1270, Tc 90.5K, Jc1100A/cm2
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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,
Bessel-like m/w power dependence
where C is the spatial layer to layer coherence
factor
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Collective Shapiro step in c-axis magnetic field
with N1270
Slightly overdoped sample 10.5 x 7.8 mm2,
N1270, Tc 90.5K, Jc1100A/cm2 N (100 /-
1.2) junctions in stack
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Collective Shapiro step in c-axis magnetic field
with N2500
In overdoped sample 16 x 9.1 x 3.8 mm3, Tc85.5K,
Jc(0)2130A/cm2
N (100 /- 1.1) 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 and field dependence
McCumber parameter
In the vortex liquid state
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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Sample preparation and characterization
Samples 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, counted from sample
thickness and branching on I-V
Structure was made by FIB two side processing
method
Yu.I. Latyshev, S.-J. Kim, Yamashita, IEEE T.
Appl. Supercond., 9, 4312 (1999)
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Microwave setup
BWO with frequency range 74 136GHz Max
radiated m/w power 30mW. Josephson junction stack
mounted on finline antenna in WR-10 waveguide,
TE01 mode
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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.
• Synchronization of Josephson oscillations in
  intrinsic stack of junctions can be achieved for
  total number of junctions under external
  microwave irradiation in c-axis magnetic field.
• Microscopically, wandering of pancakes is the
  main factor of the damping enhance and
  synchronization in the vortex liquid state
• Effectively, pancakes works as a shunts in
  every layer of Bi2Sr2CaCu2O8d

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