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Pressure effects on new high-T c superconductors
Physica 148B (1987) 289-291 North-Holland, Amsterdam
PRESSURE EFFECTS ON N E W HIGH-T c S U P E R C O N D U C T O R S
P. PRZYSgUPSKI, T. SKOSKIEWICZ, J. IGALSON and J. R A U ~ U S Z K I E W I C Z Institute of Physics, Polish Academy of Sciences, 02-668 Warszawa, Al.Lotnik6w 32/46, Poland Received 3 August 1987
The pressure dependence of the superconducting transition temperature Tc for LalsSro2CuO4, YBa2Cu307 a and EuBa2Cu307 ~ systems was measured under hydrostatic pressure up to 10 kbar. It is found that T~ Linearly increases with pressure for the La and Eu based systems. A nonlinear decrease of T~ has been observed for the Y system.
1. Introduction
Since the beginning of this year an interest in high-Tc superconducting materials has strongly stimulated extensive studies in this field. It has been shown [1] that superconductivity around 30K occurs in the L a - B a - C u - O system. An identification of Lal.sBa0.zCuO 4 phase [2] with the K2NiF 4 structure has shown that in the chemically substituted Lal.8Sr0.2CuO 4 phase Tc is near 40 K [3]. Chu et al. [4] showed that the application of pressure increased the transition temperature to about 52K. Furthermore the transition temperature about 90 K could be obtained (Wu et al. [5]). An identification of the high temperature phase was done by Cava et al. [6]. A substitution of the Y element by Eu, Nd, Sm, Gd, Ho, Er or Lu gives also high-T c orthorhombic phases [7, 8]. The effect of pressure on the superconducting transition temperature Tc has been studied for many superconducting metal systems [9]. In the conventional systems Tc usually decreases under pressure. Pressure effects on new high-Tc oxide systems were lately also reported [10, 11, 12, 13]. In this work we report the results on the pressure dependence of Tc in new high-Tc oxide systems.
tion method are given in [14-17]. The superconducting properties were checked by means of a 4 point resistance method and the susceptibility was measured using a SQUID method. Very precise X-ray characterizations of the samples were carried out by the X-ray Siemens diffractometer Kristalloflex 4. More details concerning structural and phase analysis are given elsewhere [16, 17]. Hydrostatic pressure was generated in a clamped piston cylinder apparatus with benzine as pressure transmitting medium. Pressure at low temperatures were estimated by measuring the shift of the superconducting transition temperature of pure lead placed in the high pressure chamber. We have assumed that the pressure does not change significantly in the temperature range 7-100 K. An observation of the superconducting transition of the samples was done by measuring the frequency ratio of two L C oscillating circuits supplied by the tunnel diodes. Two coils were placed in the high pressure cell and one of them contained the sample while the other a lead manometer. The relative increase in the frequency for the coil containing the sample is proportional to the decrease of the magnetic susceptibility X of the sample.
3. Results and discussion 2. Experimental details
The samples were prepared by the solid state reaction. More details concerning the prepara0378-4363/87/$03.50 © Elsevier Science Publishers B.V. (North-Holland Physics Publishing Division) and Yamada Science Foundation
Our samples of Lal.8Sr0.2CuO4_ ~ had the Tc onset at 38 K. According to X-ray analysis they contained 92% of the centred tetragonal 14/
P. Przystupski et al. / Pressure effects on new high-T c superconductors
290
[K] 37 36
La-Sr-Cu-O Eu-Bo-Cu- 0 dTc _ O . ~ r ~e_~__~ -
93 92 91 ]r-°_~
°To~ Y-Ba-Cu-O
o 90 89
o
+ b
I
I
1
2
3
~ ,
+Tci
L,
6
5
,
7 p [kbar]
Fig. 1. Superconducting transition temperature versus pressure for : × - LalsSro2CuO4, [ ] - E u B a z C u 3 0 7 a and Q, O - YBa2Cu307 a samples respectively ( T c I and Tc II are
shown in fig. 3.)
Af
I ,
I
I
]
I
1
I
I
mmm phase. Susceptibility measurements showed that above 50% of the sample was in a superconducting state. YBa2Cu30 7 ~ samples had a T~ onset at 9 6 K and zero resistance at 91.5 K. X-ray analysis indicated that they contained 95.1% of the orthorhombic phase. The Meissner effect attains a value of 75% of the ideal diamagnetism at low temperatures. Similar measurements indicated that over 68% of the E u B a z C u 3 0 v a sample was in a superconducting phase. X-ray analysis of the Eu based samples is under way. E u - B a - C u - O samples exhibited zero resistance at 93,5 K. The pressure dependence of superconducting transition temperature is shown in fig. 1 for the La, Eu and Y based systems. T c was arbitrarily determined as shown in figs. 2 and 3. The linear increase of the critical temperature was observed for the L a - S r - C u - O and E u - B a - C u - O samples. The slope dTc/d p is equal to respectively 0.12 K / k b a r and 0.05 K/kbar. In fig. 2 is presented the T~ shift under pressure 9 k b a r and at ambient pressure for the E u - B a - C u - O sample.
I
~f
X
[o.u]
x O
0 0
0.950
0 919 ~-
0 0
/
0.949
0.918
0 0
0917
O
0.916
0948
ol
O
0.915
0
0947 0946 0.945
0.91~ 0913
0944
0912
0.943
0.911
094
oo
0.910 ~
o .-
0.9~' 0940
i
86
i
I
88 90
i
I
L
92 94 96
[
I
i
9e~ 100 T[K]
Fig. 2. The temperature dependence of the oscillator frequency change ( A f / f o - --AXa c) in the superconducting transition range of an EuBazCu307_ a sample at ambient pressure open circles and crosses at 9 kbar.
I
I
70
80
i
9'0 T[K]
100
Fig. 3. The temperature dependence of the oscillator frequency change (Af/fo ~ -Axac) in the superconducting transition range at 0.3 kbar pressure for a YBa2Cu307 a sample.
P. Przyslupski et al. / Pressure effects on new high-T c superconductors
A n a n o m a l o u s b e h a v i o u r is s e e n in t h e Y - B a C u - O s a m p l e (fig. 1): t h e n e g a t i v e coefficient d T c / d p in t h e r a n g e o f l o w p r e s s u r e s . In fig. 3 t h e o s c i l l a t o r f r e q u e n c y c h a n g e in t h e s u p e r c o n d u c t i n g t r a n s i t i o n r a n g e v e r s u s t e m p e r a t u r e at 0.3 k b a r p r e s s u r e is p r e s e n t e d . T w o t r a n s i t i o n s l a b e l e d TcI a n d TcII c a n b e d i s t i n g u i s h e d . T h e d e p e n d e n c e s o f TcI a n d TcII v e r s u s p r e s s u r e a r e p r e s e n t e d in fig. 1. S i m i l a r m e a s u r e m e n t s o n t h e Yl_xEuxBazCU3OT_~ a r e u n d e r way. I n c o n c l u s i o n w e o b s e r v e d t h e influence o f p r e s s u r e o n T~ in L a - S r - C u - O , Eu-Ba-Cu-O and Y-Ba-Cu-O systems and the linear increase of T~ for L a a n d E u b a s e d systems. T h e r e c e i v e d v a l u e o f t h e s l o p e s d T c / d p was 0.12 K / k b a r a n d 0.05 K / k b a r for t h e L a a n d E u b a s e d s y s t e m s . Y based systems indicated a double transition and a slightly n e g a t i v e s l o p e at low p r e s s u r e . O u r resuits for L a - S r - C u - O and Y-Ba-Cu-O differ f r o m t h e d a t a p r e s e n t e d b y C h u et al. [4] - w e d o n o t o b s e r v e such a s t r o n g gain o f Tc for L a - S r Cu-O.
References [1] J.G. Bednorz and K.A. Mueller, Z. Phys. B 64 (1986) 189. [2] S. Uchida, H. Takagi, K. Kitazawa and S. Tanaka, Jpn. J. Appl. Phys. 26 (1987) L1. [3] R.J. Cava, R.B. van Dover, B. Batlogg and E.A. Rietman, Phys. Rev. Lett. 58 (1987) 408.
291
[4] C.W. Chu, P.H. Hor, R.L. Meng, L. Gao, Z.J. Huang and Y.Q. Wang, Phys. Rev. Lett. 58 (1987) 405. [5] M.K. Wu, J.R. Ashburn, C.J. Tong, P.H. Hor, R.C. Meng, L. Gao, Z.J. Huang, Y.Q. Wang and C. Chu, Phys. Rev. Lett. 58 (1987) 908. [6] R.J. Cava, B. Batlogg, R.B. van Dover, D.W. Murphy, S. Sunshine, T. Siegrist, J.P. Remeika, E.A. Rietman, S. Zahurak and G.P. Espinosa, Phys. Rev. Lett. 58 (1987) 576. [7] D.W. Murphy, S. Sunshine, R.B. van Dover, R.J. Cava, B. Batlogg, S.M. Zahurak and L.F. Schneemeyer, Phys. Rev. Lett. 58 (1978) 188. [8] P.H. Hor, R.L. Meng, Y.Q. Wang, L. Gao, Z.J. Huang, J. Bechtold, K. Forster and C.W. Chu, Phys. Rev. Lett. 58 (1987) 891. [9] See: Superconductivity, (Parks and Dekker, New York, 1969), p. 771. [10] M. Sato, M. Onodu, S. Shamoto, S. Hosoya and Y. Masuyama, preprint. [11] C. Politis, J. Geerk, M. Dietrich and B. Obst, Z. Phys. B 66 (1987) 141. [12] S. Yomo, Ch. Murayama, H. Takahashi, N. Mori, K. Kishio, K. Kitazawa and K. Fueki, Jap. J. Appl. Phys. 26 (1987) L603. [13] K. Murata, H. Ihara, M. Tokumoto, M. Minebuyashi, N. Terada, K. Senzaki and Y. Kimura, Jap. J. Appl. Phys. 26 (1987) L471. [14] P. Przyslupski, J. Igalson, J. Rauluszkiewicz and T. Sko~kiewicz, Phys. Rev. B 36 (1987) 743. [15] P. Przyslupski, J. Igalson, W. Dobrowolski and J. Rautuszkiewicz, submitted to LT-18 Conf. August (1987) Kyoto. [16] K. Godwod, J. G6recka, G. Jasiotek, J. Majewski and P. Przyslupski, Z. Phys. B 67 (1987) 313. [17] K. Godwod, J. Gfrecka, J. Majewski, J. Igalson, P. Przystupski and J. Rauluszkiewicz, submitted to Z. Phys. B. in press (1987).
PRESSURE EFFECTS ON N E W HIGH-T c S U P E R C O N D U C T O R S
P. PRZYSgUPSKI, T. SKOSKIEWICZ, J. IGALSON and J. R A U ~ U S Z K I E W I C Z Institute of Physics, Polish Academy of Sciences, 02-668 Warszawa, Al.Lotnik6w 32/46, Poland Received 3 August 1987
The pressure dependence of the superconducting transition temperature Tc for LalsSro2CuO4, YBa2Cu307 a and EuBa2Cu307 ~ systems was measured under hydrostatic pressure up to 10 kbar. It is found that T~ Linearly increases with pressure for the La and Eu based systems. A nonlinear decrease of T~ has been observed for the Y system.
1. Introduction
Since the beginning of this year an interest in high-Tc superconducting materials has strongly stimulated extensive studies in this field. It has been shown [1] that superconductivity around 30K occurs in the L a - B a - C u - O system. An identification of Lal.sBa0.zCuO 4 phase [2] with the K2NiF 4 structure has shown that in the chemically substituted Lal.8Sr0.2CuO 4 phase Tc is near 40 K [3]. Chu et al. [4] showed that the application of pressure increased the transition temperature to about 52K. Furthermore the transition temperature about 90 K could be obtained (Wu et al. [5]). An identification of the high temperature phase was done by Cava et al. [6]. A substitution of the Y element by Eu, Nd, Sm, Gd, Ho, Er or Lu gives also high-T c orthorhombic phases [7, 8]. The effect of pressure on the superconducting transition temperature Tc has been studied for many superconducting metal systems [9]. In the conventional systems Tc usually decreases under pressure. Pressure effects on new high-Tc oxide systems were lately also reported [10, 11, 12, 13]. In this work we report the results on the pressure dependence of Tc in new high-Tc oxide systems.
tion method are given in [14-17]. The superconducting properties were checked by means of a 4 point resistance method and the susceptibility was measured using a SQUID method. Very precise X-ray characterizations of the samples were carried out by the X-ray Siemens diffractometer Kristalloflex 4. More details concerning structural and phase analysis are given elsewhere [16, 17]. Hydrostatic pressure was generated in a clamped piston cylinder apparatus with benzine as pressure transmitting medium. Pressure at low temperatures were estimated by measuring the shift of the superconducting transition temperature of pure lead placed in the high pressure chamber. We have assumed that the pressure does not change significantly in the temperature range 7-100 K. An observation of the superconducting transition of the samples was done by measuring the frequency ratio of two L C oscillating circuits supplied by the tunnel diodes. Two coils were placed in the high pressure cell and one of them contained the sample while the other a lead manometer. The relative increase in the frequency for the coil containing the sample is proportional to the decrease of the magnetic susceptibility X of the sample.
3. Results and discussion 2. Experimental details
The samples were prepared by the solid state reaction. More details concerning the prepara0378-4363/87/$03.50 © Elsevier Science Publishers B.V. (North-Holland Physics Publishing Division) and Yamada Science Foundation
Our samples of Lal.8Sr0.2CuO4_ ~ had the Tc onset at 38 K. According to X-ray analysis they contained 92% of the centred tetragonal 14/
P. Przystupski et al. / Pressure effects on new high-T c superconductors
290
[K] 37 36
La-Sr-Cu-O Eu-Bo-Cu- 0 dTc _ O . ~ r ~e_~__~ -
93 92 91 ]r-°_~
°To~ Y-Ba-Cu-O
o 90 89
o
+ b
I
I
1
2
3
~ ,
+Tci
L,
6
5
,
7 p [kbar]
Fig. 1. Superconducting transition temperature versus pressure for : × - LalsSro2CuO4, [ ] - E u B a z C u 3 0 7 a and Q, O - YBa2Cu307 a samples respectively ( T c I and Tc II are
shown in fig. 3.)
Af
I ,
I
I
]
I
1
I
I
mmm phase. Susceptibility measurements showed that above 50% of the sample was in a superconducting state. YBa2Cu30 7 ~ samples had a T~ onset at 9 6 K and zero resistance at 91.5 K. X-ray analysis indicated that they contained 95.1% of the orthorhombic phase. The Meissner effect attains a value of 75% of the ideal diamagnetism at low temperatures. Similar measurements indicated that over 68% of the E u B a z C u 3 0 v a sample was in a superconducting phase. X-ray analysis of the Eu based samples is under way. E u - B a - C u - O samples exhibited zero resistance at 93,5 K. The pressure dependence of superconducting transition temperature is shown in fig. 1 for the La, Eu and Y based systems. T c was arbitrarily determined as shown in figs. 2 and 3. The linear increase of the critical temperature was observed for the L a - S r - C u - O and E u - B a - C u - O samples. The slope dTc/d p is equal to respectively 0.12 K / k b a r and 0.05 K/kbar. In fig. 2 is presented the T~ shift under pressure 9 k b a r and at ambient pressure for the E u - B a - C u - O sample.
I
~f
X
[o.u]
x O
0 0
0.950
0 919 ~-
0 0
/
0.949
0.918
0 0
0917
O
0.916
0948
ol
O
0.915
0
0947 0946 0.945
0.91~ 0913
0944
0912
0.943
0.911
094
oo
0.910 ~
o .-
0.9~' 0940
i
86
i
I
88 90
i
I
L
92 94 96
[
I
i
9e~ 100 T[K]
Fig. 2. The temperature dependence of the oscillator frequency change ( A f / f o - --AXa c) in the superconducting transition range of an EuBazCu307_ a sample at ambient pressure open circles and crosses at 9 kbar.
I
I
70
80
i
9'0 T[K]
100
Fig. 3. The temperature dependence of the oscillator frequency change (Af/fo ~ -Axac) in the superconducting transition range at 0.3 kbar pressure for a YBa2Cu307 a sample.
P. Przyslupski et al. / Pressure effects on new high-T c superconductors
A n a n o m a l o u s b e h a v i o u r is s e e n in t h e Y - B a C u - O s a m p l e (fig. 1): t h e n e g a t i v e coefficient d T c / d p in t h e r a n g e o f l o w p r e s s u r e s . In fig. 3 t h e o s c i l l a t o r f r e q u e n c y c h a n g e in t h e s u p e r c o n d u c t i n g t r a n s i t i o n r a n g e v e r s u s t e m p e r a t u r e at 0.3 k b a r p r e s s u r e is p r e s e n t e d . T w o t r a n s i t i o n s l a b e l e d TcI a n d TcII c a n b e d i s t i n g u i s h e d . T h e d e p e n d e n c e s o f TcI a n d TcII v e r s u s p r e s s u r e a r e p r e s e n t e d in fig. 1. S i m i l a r m e a s u r e m e n t s o n t h e Yl_xEuxBazCU3OT_~ a r e u n d e r way. I n c o n c l u s i o n w e o b s e r v e d t h e influence o f p r e s s u r e o n T~ in L a - S r - C u - O , Eu-Ba-Cu-O and Y-Ba-Cu-O systems and the linear increase of T~ for L a a n d E u b a s e d systems. T h e r e c e i v e d v a l u e o f t h e s l o p e s d T c / d p was 0.12 K / k b a r a n d 0.05 K / k b a r for t h e L a a n d E u b a s e d s y s t e m s . Y based systems indicated a double transition and a slightly n e g a t i v e s l o p e at low p r e s s u r e . O u r resuits for L a - S r - C u - O and Y-Ba-Cu-O differ f r o m t h e d a t a p r e s e n t e d b y C h u et al. [4] - w e d o n o t o b s e r v e such a s t r o n g gain o f Tc for L a - S r Cu-O.
References [1] J.G. Bednorz and K.A. Mueller, Z. Phys. B 64 (1986) 189. [2] S. Uchida, H. Takagi, K. Kitazawa and S. Tanaka, Jpn. J. Appl. Phys. 26 (1987) L1. [3] R.J. Cava, R.B. van Dover, B. Batlogg and E.A. Rietman, Phys. Rev. Lett. 58 (1987) 408.
291
[4] C.W. Chu, P.H. Hor, R.L. Meng, L. Gao, Z.J. Huang and Y.Q. Wang, Phys. Rev. Lett. 58 (1987) 405. [5] M.K. Wu, J.R. Ashburn, C.J. Tong, P.H. Hor, R.C. Meng, L. Gao, Z.J. Huang, Y.Q. Wang and C. Chu, Phys. Rev. Lett. 58 (1987) 908. [6] R.J. Cava, B. Batlogg, R.B. van Dover, D.W. Murphy, S. Sunshine, T. Siegrist, J.P. Remeika, E.A. Rietman, S. Zahurak and G.P. Espinosa, Phys. Rev. Lett. 58 (1987) 576. [7] D.W. Murphy, S. Sunshine, R.B. van Dover, R.J. Cava, B. Batlogg, S.M. Zahurak and L.F. Schneemeyer, Phys. Rev. Lett. 58 (1978) 188. [8] P.H. Hor, R.L. Meng, Y.Q. Wang, L. Gao, Z.J. Huang, J. Bechtold, K. Forster and C.W. Chu, Phys. Rev. Lett. 58 (1987) 891. [9] See: Superconductivity, (Parks and Dekker, New York, 1969), p. 771. [10] M. Sato, M. Onodu, S. Shamoto, S. Hosoya and Y. Masuyama, preprint. [11] C. Politis, J. Geerk, M. Dietrich and B. Obst, Z. Phys. B 66 (1987) 141. [12] S. Yomo, Ch. Murayama, H. Takahashi, N. Mori, K. Kishio, K. Kitazawa and K. Fueki, Jap. J. Appl. Phys. 26 (1987) L603. [13] K. Murata, H. Ihara, M. Tokumoto, M. Minebuyashi, N. Terada, K. Senzaki and Y. Kimura, Jap. J. Appl. Phys. 26 (1987) L471. [14] P. Przyslupski, J. Igalson, J. Rauluszkiewicz and T. Sko~kiewicz, Phys. Rev. B 36 (1987) 743. [15] P. Przyslupski, J. Igalson, W. Dobrowolski and J. Rautuszkiewicz, submitted to LT-18 Conf. August (1987) Kyoto. [16] K. Godwod, J. G6recka, G. Jasiotek, J. Majewski and P. Przyslupski, Z. Phys. B 67 (1987) 313. [17] K. Godwod, J. Gfrecka, J. Majewski, J. Igalson, P. Przystupski and J. Rauluszkiewicz, submitted to Z. Phys. B. in press (1987).