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Observation of the flux line lattice in high Tc-superconductor Bi2.2Sr2CaCu2OX and Ti2Ba2CaCu2OX single crystals
~
Solld State Communications, Printed in Great Britain.
Vol. 70, No. 12, pp. 1145-1146,
OBSERVATION
OF THE
FLUX
Bi2.2Sr2CaCu2Ox L.Ya.Vinnikov,
Institute
AND
TI2Ba2CaCu20
M.P.Kulakov,
T -SUPERCONDUCTOR c x SINGLE CR¥STAI~
G.A.Emelchenko, D.Ya.Lenchinenko
of Solid State Physics USSR Chernogolovka. Moscow district, (Received
0038-1098/8953.00+.00 Pergamon Press plc
LINE LATTICE IN HIGH
L.A.Gurevicb,
N.N.Kolesnikov,
1989.
20 April
1989
G.A.Kazaryan, and
Academy 142432,
Yu.A.Ossipyan of USSR
Sciences,
by V.M.Agran0vich)
The flux-line lattice (FLL) has been observed on the (001) face of high T c Bi2.2Sr2CaCu20 X and TI2Ba2CaCu20 X single cristals using the technique of decorating the sample with small ferromagnetic particles. Strong pinning of the Abrikosov vortices by plane defects along (i00) and (010) planes has been found out on Bi2.2Sr2CaCu20 X. The triangular FLL with a long-range order has
been
observed
on
the
perfect
TI2Ba2CaCu20
penetration depth for a magnetic been evaluated as K0.2pm at 4.2K
The recent
observation
superconductor
of
the
YBa2Cu3Oxsingle
FLL i n crystal
high-T
to
be very fruitful. They allowed determination of the value of, mae~efic flux contained in a 1,~ -,. single vortex ,direct observation of attraction of vortices to twin boundaries~ and finding out the anisotr~py of superconducting properties in (001) plane . That is why, it is interesting, to investigate the FLL in new families of high-T c •
.
superconductors~ ~ u c h as TI-Ba-Ca-Cu-O -'--. The samples under
Bi2.2Sr2CaCu20x
crystals were molten mixture
Bi-Sr-Ca-Cu-O investigation
and T12Ba2CaCu20x s i n g l e
produced as follows,
.
and were
crystals
Bi2.2Sr2CaCu20 X single-
grown by slow cooling of a of 1 ~ 2 0 3 , CuO, SrCO 3, SrCO 3 w i t h
mole composition Bi:Sr:Ca:Cu=2:3:3:4. As a result, we h a d t ~ e s t a c k s o f f i n e s i n g l e - c r y s t a l plates (~ 151 R~n~). T h e y s h o w e d a n o n s e t a t - 8 4 E and zero resistance ~69 K. T12B~2CaCu20 X s i n g l e -crystals were grown from molten mixture of T 1 2 0 3 , CaO, BaO, CuO, u s i n g t h e m e t h o d o f temperature gradient. They had ~elementary cell dimensions a=b=3.858, c=29.318 ~ and showed an onset at-ll0 K and zero resistance a t ~-104 K. During the experiments the samples were cooled in the transverse magnetic field perpendicular" to the plane (001) from2!~T down to 4.2 K and then decorated similar' to ' . We used external mo~o-netic field from i0 to 60 Oe. In TI2Ba2CaCu20 X single crystals the as-grown surface was
decorated,
but
in
Bi 2 .2St-2CaCu2Ox
the
spelling one was used. In any case the decorated surface was parallel to (00I) plane. Fig. I shows the t y p i ( : a l section of' Bi2.2Sr2CaCu2Ox single-crystal surface after
single
crystal.The (001)
axis
has
decoration. T h i s p h o t o was t a k e n i n t h e s c a n n i n g electron microscope, where the aggregations of
c
proved
~._
field parallel to for beth materials.
small ferromagnetic particles, which decorated the Abrikosov vortices, looked like bright points. As one can distinctly see, there are bands of high
vortex density along [100] and [010] directions. Vortex are symmetrically distributed in some of the bands (fig.2). It proves these pinning centers are not grown steps, but rather bulk defects parallel to (100) and (010) planes. At the Bi2.2Sr2CaCu20 X single-crystal surface in polarized light we have observed the additional contrast, which looked like the domains with changing colors when rotating the sample. However, the boundaries of these domains did not correspond to the pinning bands. We hope to discuss the nature of pinning centers in Bi2.2~r2CaCu2Ox single-crystals elsewhere. In
the
most
perfect
TI2Ba2CaCuzO
X
single
crystal we observed the regular triangular FLL with large dimensions of correlation regions through the whole surface of the sample (fig.3). A hexagonal sy,unetry of the FLL (see diffraction pattern in fig.2) and absence of any relation of the FLL with the crystallografic axes indicated the isotropy of (001) plane Tl2Ba2CaCu2Ox(unlike
YBa2Cu3Ox4). The
less
perfect
Tl2Ba2Ca~u20
x single
crystals had a flux line structure,which looked like an intermediate mixed state with irregular distribution of vortices in the mixed-state domains.We suppose it testifies to the short-range order of the FI,L, which was already observed in high T c superconductors, it is likely to be associated with l i t t l e pe~fection of the crystals used, but not with thermal fluctuation. Moreover, we have confirmed that each vortex is containirN a flux quantum ~0=hc/2e in both
i145
0BSERVATION OF THE FLUX LINE LATTICE
1146
Vol. 70, No. 12
(b
(~)
I
o
Fig.l.
Flux line
single
crystal.
H-~20
e vortex
Oe;(a}
overview
line
crystal.
in
external
distribution
Fig.2.Flux single
lattice The
of
gi2.2Sr2L~Cu20X magnetic
decorated
field
surface;
is (b)
i n the p i r m i n g band.
lattice The
in pertect external
T1213a2CaCu20 x
magnetic
field
is
H ~35 Oe. e materials. From t h e d i m e n s i o n s o f t h e d e c o r a t e d region we h a v e e v a l u a t e d t h e p e n e t r a t i o n depth a s ~ 0 . 2 g~ f o r both materials ( similar to Y~2Cu3Ox~).
ACIt~'O~E1)G]~VI'S We a r e very greateful to S.Khasanov for his kindly giving the results of X ray measurements ~ld to L.G. I s a e v a and V.A.APhitK~v f o r a s s i s t a n c e .
RFFFI4FNCF~ i.
P.I..Ceunme], D . J . B i s h o p , G.J.Dolan, J.R.Cwo, C.A.Murray, l . . F . S n e e m e y e r & ,J.V.Waszczak, Ph.vs. [~ev. L e t t 5 9 , no. 22, 2 5 9 2 { 1 9 8 7 ) 2. I . . ¥ a . V i t m i k o v , [ , . A . G u r e v i c h . G . A . F m e l c h e n k o & Y u . A . O s f i [ p y a n , S o ~ . t)~
4.
5,
L.Ya. V i n n i h o v . l . V , G r i g o r ' e v a , L,A.Gurevieh, & Y u . A . O s s i p y a n . Soy. P & v s . J h T F L e t t . 4 9 , no.2. 83 ( 1 9 8 8 ) . C.Miche]
,
M.Hervieu,
M.
M.Borei,
A.Grandin,
F.[)eslandes, J . P r o v , . ~ t & E . R a v e a u . Z . P h y s . B 68, 421 ( 1 9 8 7 ) . {3. Z.Z.Sherk~. ~ ' . K i e h l , J.P, e n n e i t . A.E1 A l l , D . M a r s h , G. D. Mooney, F. Araramash, J. Smith, D. V i a r & A.M.Hermann, , 4 p I . P ! t v : ; . L e t t . 5 2 , 1738 ( 1 9 8 8 )
Solld State Communications, Printed in Great Britain.
Vol. 70, No. 12, pp. 1145-1146,
OBSERVATION
OF THE
FLUX
Bi2.2Sr2CaCu2Ox L.Ya.Vinnikov,
Institute
AND
TI2Ba2CaCu20
M.P.Kulakov,
T -SUPERCONDUCTOR c x SINGLE CR¥STAI~
G.A.Emelchenko, D.Ya.Lenchinenko
of Solid State Physics USSR Chernogolovka. Moscow district, (Received
0038-1098/8953.00+.00 Pergamon Press plc
LINE LATTICE IN HIGH
L.A.Gurevicb,
N.N.Kolesnikov,
1989.
20 April
1989
G.A.Kazaryan, and
Academy 142432,
Yu.A.Ossipyan of USSR
Sciences,
by V.M.Agran0vich)
The flux-line lattice (FLL) has been observed on the (001) face of high T c Bi2.2Sr2CaCu20 X and TI2Ba2CaCu20 X single cristals using the technique of decorating the sample with small ferromagnetic particles. Strong pinning of the Abrikosov vortices by plane defects along (i00) and (010) planes has been found out on Bi2.2Sr2CaCu20 X. The triangular FLL with a long-range order has
been
observed
on
the
perfect
TI2Ba2CaCu20
penetration depth for a magnetic been evaluated as K0.2pm at 4.2K
The recent
observation
superconductor
of
the
YBa2Cu3Oxsingle
FLL i n crystal
high-T
to
be very fruitful. They allowed determination of the value of, mae~efic flux contained in a 1,~ -,. single vortex ,direct observation of attraction of vortices to twin boundaries~ and finding out the anisotr~py of superconducting properties in (001) plane . That is why, it is interesting, to investigate the FLL in new families of high-T c •
.
superconductors~ ~ u c h as TI-Ba-Ca-Cu-O -'--. The samples under
Bi2.2Sr2CaCu20x
crystals were molten mixture
Bi-Sr-Ca-Cu-O investigation
and T12Ba2CaCu20x s i n g l e
produced as follows,
.
and were
crystals
Bi2.2Sr2CaCu20 X single-
grown by slow cooling of a of 1 ~ 2 0 3 , CuO, SrCO 3, SrCO 3 w i t h
mole composition Bi:Sr:Ca:Cu=2:3:3:4. As a result, we h a d t ~ e s t a c k s o f f i n e s i n g l e - c r y s t a l plates (~ 151 R~n~). T h e y s h o w e d a n o n s e t a t - 8 4 E and zero resistance ~69 K. T12B~2CaCu20 X s i n g l e -crystals were grown from molten mixture of T 1 2 0 3 , CaO, BaO, CuO, u s i n g t h e m e t h o d o f temperature gradient. They had ~elementary cell dimensions a=b=3.858, c=29.318 ~ and showed an onset at-ll0 K and zero resistance a t ~-104 K. During the experiments the samples were cooled in the transverse magnetic field perpendicular" to the plane (001) from2!~T down to 4.2 K and then decorated similar' to ' . We used external mo~o-netic field from i0 to 60 Oe. In TI2Ba2CaCu20 X single crystals the as-grown surface was
decorated,
but
in
Bi 2 .2St-2CaCu2Ox
the
spelling one was used. In any case the decorated surface was parallel to (00I) plane. Fig. I shows the t y p i ( : a l section of' Bi2.2Sr2CaCu2Ox single-crystal surface after
single
crystal.The (001)
axis
has
decoration. T h i s p h o t o was t a k e n i n t h e s c a n n i n g electron microscope, where the aggregations of
c
proved
~._
field parallel to for beth materials.
small ferromagnetic particles, which decorated the Abrikosov vortices, looked like bright points. As one can distinctly see, there are bands of high
vortex density along [100] and [010] directions. Vortex are symmetrically distributed in some of the bands (fig.2). It proves these pinning centers are not grown steps, but rather bulk defects parallel to (100) and (010) planes. At the Bi2.2Sr2CaCu20 X single-crystal surface in polarized light we have observed the additional contrast, which looked like the domains with changing colors when rotating the sample. However, the boundaries of these domains did not correspond to the pinning bands. We hope to discuss the nature of pinning centers in Bi2.2~r2CaCu2Ox single-crystals elsewhere. In
the
most
perfect
TI2Ba2CaCuzO
X
single
crystal we observed the regular triangular FLL with large dimensions of correlation regions through the whole surface of the sample (fig.3). A hexagonal sy,unetry of the FLL (see diffraction pattern in fig.2) and absence of any relation of the FLL with the crystallografic axes indicated the isotropy of (001) plane Tl2Ba2CaCu2Ox(unlike
YBa2Cu3Ox4). The
less
perfect
Tl2Ba2Ca~u20
x single
crystals had a flux line structure,which looked like an intermediate mixed state with irregular distribution of vortices in the mixed-state domains.We suppose it testifies to the short-range order of the FI,L, which was already observed in high T c superconductors, it is likely to be associated with l i t t l e pe~fection of the crystals used, but not with thermal fluctuation. Moreover, we have confirmed that each vortex is containirN a flux quantum ~0=hc/2e in both
i145
0BSERVATION OF THE FLUX LINE LATTICE
1146
Vol. 70, No. 12
(b
(~)
I
o
Fig.l.
Flux line
single
crystal.
H-~20
e vortex
Oe;(a}
overview
line
crystal.
in
external
distribution
Fig.2.Flux single
lattice The
of
gi2.2Sr2L~Cu20X magnetic
decorated
field
surface;
is (b)
i n the p i r m i n g band.
lattice The
in pertect external
T1213a2CaCu20 x
magnetic
field
is
H ~35 Oe. e materials. From t h e d i m e n s i o n s o f t h e d e c o r a t e d region we h a v e e v a l u a t e d t h e p e n e t r a t i o n depth a s ~ 0 . 2 g~ f o r both materials ( similar to Y~2Cu3Ox~).
ACIt~'O~E1)G]~VI'S We a r e very greateful to S.Khasanov for his kindly giving the results of X ray measurements ~ld to L.G. I s a e v a and V.A.APhitK~v f o r a s s i s t a n c e .
RFFFI4FNCF~ i.
P.I..Ceunme], D . J . B i s h o p , G.J.Dolan, J.R.Cwo, C.A.Murray, l . . F . S n e e m e y e r & ,J.V.Waszczak, Ph.vs. [~ev. L e t t 5 9 , no. 22, 2 5 9 2 { 1 9 8 7 ) 2. I . . ¥ a . V i t m i k o v , [ , . A . G u r e v i c h . G . A . F m e l c h e n k o & Y u . A . O s f i [ p y a n , S o ~ . t)~
4.
5,
L.Ya. V i n n i h o v . l . V , G r i g o r ' e v a , L,A.Gurevieh, & Y u . A . O s s i p y a n . Soy. P & v s . J h T F L e t t . 4 9 , no.2. 83 ( 1 9 8 8 ) . C.Miche]
,
M.Hervieu,
M.
M.Borei,
A.Grandin,
F.[)eslandes, J . P r o v , . ~ t & E . R a v e a u . Z . P h y s . B 68, 421 ( 1 9 8 7 ) . {3. Z.Z.Sherk~. ~ ' . K i e h l , J.P, e n n e i t . A.E1 A l l , D . M a r s h , G. D. Mooney, F. Araramash, J. Smith, D. V i a r & A.M.Hermann, , 4 p I . P ! t v : ; . L e t t . 5 2 , 1738 ( 1 9 8 8 )