Ideas which led to the discovery of High- temperature superconductors. A didactic demonstration of Nobel Lecture report.

1. Ideas leading to discovery of High- Temperature
Superconductivity in Cuprates
Vivek Kumar Bhartiya
Vivek.Bhartiya@skolkovotech.ru
Skolkovo Institute of Science and Technology
Cubic niobium alloys copper oxides perovskite

2. 2
CRTITICALPHASEDIAGRAM
Tc (K)
Al 1.2
Pb 7.2
Sn 3.7
Nb3 Sn 18
H2S 203
YBCO 90
BaFe2 As2 50
160
Conventional
Superconductor
Unconventional
(HTS)
Superconductor

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3
Low temperature experimentalist-
structural and ferroelectric properties
of perovskite solid-solution crystal
IBM Research Division, Zurich Research
Laboratory, expertise in insulating oxides
SrTiO3 & LaAlO3
J. Georg Bednorz HR@ IBM, 1978
(STM) 1986
SrTiO3 + Nb ( to increase n = 2* 1020 /cm3)  Niobium reduced material instead of simply reduced,
Tc = 0.7K .
SrTiO3 + Nb +Nb…..1.2K
Gerd Binnig
Superconductivity and
tunneling
Plasma edge passes the highest phonon - shielding
Baratoff, A. and Binnig, G. (1981) Physica 108B, 1335; Baratoff, A., Binnig, G.,
Bednorz, J. G., Gervais, F., and Servoin, J. L. (1982) in: Superconductivity in dand
f-Band Metals, Proceedings IV Conference on Superconductivily in d- and f-Band
Metals, editors W. Buckel and W. Weber (Kernforschungszentrum Karlsruhe)
p. 419.

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T. Schneider and E. Stoll, Physica 55,702 (1971)
K. Alex Muller
Granular Superconductivity-Tc-
2.8K, 1.1K in pure Al, ESR
experiments on transition metal
impurities in the perovskite host
lattice
Possibility of High-temperature superconductivity in metallic H. 100K , 2-3 Megabar
SrTiO3 + H  Not enough DOE for metallic state . 0.3K if reduced. Hey Bednorz, would
you like to work on
superconductivity?
(1986)
Schooley, J. F., Frederikse, H. P. R., Hosler, W. R., and Pfeiffer, E. R. (1967) Phys. Rev. 159, 301.

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1973 : Li- Ti-O system – Multiphase sample
-Presence of different phases
-Difficult in preparation
Johnston, D. C., Prakash, H., Zachariasen, W. H., and Viswanathan, R. (1973) Mat. Res. Bull. 8, 777.
Sleight, A. W., Gillson, J. L., and Bierstedt, P. E. (1975) Solid State Commun. 17, 27.
1975 : Single-phase sample
-Single phases
-Easy preparation
- Thin film device applications- U.S. and Japan
Ba Pb1-x Bix O3 Tc~ 13K
Li1+x Ti2-x O4 Tc~ 13K
n= 4 * 10 21 /cm3
One can vary one of
these numbers to
control Tc.

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Chakraverty, B. K. (1979) J. Physique Lett. 40, L99; idem (1981) J. Physique 42, 1351.
λ= N(EF) V
Bipolar model based on the mixed vacancies.
Jahn- Teller polaron model
Höck, K.-H., Nickisch, H., and Thomas, H. (1983) Helv. Phys. Acta 56, 237.
Linear chain model for narrow-band IMC
results--
EJT << BandWidth = slight perturbation
EJT < BandWidth = tendency to localization
EJT ~ |BandWidth| = polaron
Now question was, in
which systems to look
for superconductive
transition????

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Ni3+ , Fe3+ , Cu2+ - partially filled (eg) oxides
1983
La-Ni-O, LaNiO3 , metallic conductor
La-Al- Ni-O, La Al1-xNixO3 , localization at low temp
La-Y- Ni-O, Lax Al1-xNiO3 , localization at low temp
Would the path we decided to embark upon finally lead into a blind alley?

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Ni3+ , Fe3+ , Cu2+ - partially filled (eg) oxides
1985
La-Ni-O, LaNiO3 , metallic conductor
La-Non JT Cu2+ - Ni-O, La Cu1-xNixO3, increased absolute value of
resistance
However, the metallic character of the solid solutions was preserved down
to 4K. No indication of superconductivity. Time to study literature.
Received new experimental support
Goodenough, J. B. and Longo, M. (1970, “Magnetic and other properties of oxide and related compounds” In: Landoldt-
Boernstein New Series. Vol. III/4a:
Crystal and Solid State Physics, editors K. H. Hellwege and A. M. Hellwege
(Springer-Verlag, Berlin, Heidelberg, New York), p. 262, Fig. 73.

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Michel, C., Er-Rakho, L., and Raveau, B. (1985) Mat. Res. Bull. 20, 667.
Ba- La-Cu perovskite exhibiting metallic conductivity in the temperature range 300-1000 C.
All four property fulfilled by this material
x Ba 0.75
Suzuki, M., Murakami, T., and Inamura, T. (1981) Shinku 24, 67; Enomoto,
Y., Suzuki, M., Murakami, T., Inukai, T., and Inamura, T. (1981) Jpn. J.
Appl. Phys. 20, L661.
Decrease in resistance
shows similarity with
superconductivity in
granular materials.
X-Ray diffraction pattern of two-phase sample with Ba : La = 0.08. The second phase
occurring with the K2NeF-type phase indicated by open circles.

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“I turned to be a stroke of luck, in the sense that the compound we wanted
to form was not superconducting”
“Which is the compound where the mixed valency of the copper leads to
the superconductive transition”
Bednorz, J. G. and Müller, K. A. (1986) ‘Z. Phys. B 64, 189.
La2CuO4
Orthorhombic to tetragonal phase transition. Ba/La ratio: 1= 0,03, 2= 0,06, 3= 0,07

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Susceptibility Measurement

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Wu, M. K., Ashburn, J. R., Torng, C. J., Hor, P. H., Meng, R. L., Goa, I..,
Huang, Z. J., Wang, Y. Q., and Chu, C. W. (1987) Phys. Rev. Lett. 58. 908;
Hor, P. H., Gao, L., Meng, R. L., Huang, Z. J., Wang, Y. Q., Forster, K.,
Vassilious, J., Chu, C. W., Wu, M. K., Ashburn, J. R., and Torng, C. J. (1987)
ibid., 91 1.
La3+ and Sr3+ same ionic radius

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Yttrium Barium Copper Oxides Cuprate
Questions??