Upper critical magnetic fields Hc2(T) have been measured resistively for the high‐temperature (Tc≳90 K) superconductors TmBa2Cu3O9−δ and YBa2Cu3O9−δ in applied magnetic fields H up to 9 T. If H at the resistive midpoint is defined as Hc2, then the upper critical field slopes (dHc2/dT)Tc at the superconducting transition temperatures Tc are respectively −2.8 and −1.1 T/K. The Tm‐specimen initial slope is apparently the highest yet reported for 90 K superconductors. Extrapolations from this slope, based on standard, three‐dimensional, dirty‐limit Werthamer, Helfand, Hohenberg, and Maki theory, yield (1) zero‐temperature upper critical fields Hc2(T=0)=99–175 T, where the range is determined by the degree of paramagnetic limitation; (2) Hc2(T=77 K)≊36 T, the upper critical field at the boiling point of liquid nitrogen.

Topics
Paramagnetic materials, Superconductivity, Superconductors, Chemical elements, Transition metal oxides
1.
M. K.
Wu
,
J. R.
Ashburn
,
C. T.
Torng
,
P. H.
Hor
,
R. L.
Meng
,
L.
Gao
,
Z. J.
Huang
,
Y. Q.
Wang
, and
C. H.
Chu
,
Phys. Rev. Lett.
58
,
908
(
1987
).
Crossref
Search ADS
PubMed
 
2.
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.
Espmosa
,
Phys. Rev. Lett.
58
,
1676
(
1987
).
Crossref
Search ADS
PubMed
 
3.
R.
Beyers
,
G.
Lim
,
E. M.
Engler
,
R. J.
Savoy
,
T. M.
Shaw
,
T. R.
Dinger
,
W. J.
Gallagher
, and
R. L.
Sandstrom
,
Appl. Phys. Lett.
50
,
1918
(
1987
).
Crossref
Search ADS
 
4.
M. A. Beno, L. Soderholm, D. W. Capone, II, D. G. Hinks, J. D. Jorgensen, I. K. Schuller, C. U. Segre, K. Zhang, and J. D. Grace (unpublished).
5.
K. N. Yang, Y. Dalichaouch, J. M. Ferreira, B. W. Lee, J. J. Neumeier, M. S. Torikachvili, H. Zhou, M. B. Maple, and R. R. Hake, Solid State Commun. (to be published).
6.
K. N. Yang, Y. Dalichaouch, J. M. Ferreira, R. R. Hake, B. W. Lee, M. B. Maple, J. J. Neumeier, M. S. Torikachvili, and H. Zhou, Proceedings of the Materials Research Society, Anaheim Meeting, edited by D. U. Gubser and M. Schluter (Materials Research Society, Pittsburgh, PA, 1987), pp. 77–79.
7.
E. M. Engler, V. Y. Lee, A. I. Nazzal, R. Beyers, G. Lim, P. M. Grant, S. S. P. Parkin, M. L. Ramirez, J. E. Vasquez, and R. J. Savoy (unpublished).
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
,
1891
(
1987
).
Crossref
Search ADS
PubMed
 
9.
M. B. Maple, K. N. Yang, M. S. Torikachvili, J. M. Ferreira, J. J. Neumeier, H. Zhou, Y. Dalichaouch, and B. W. Lee, Solid State Commun. (to be published).
10.
Z. Fisk, J. D. Thompson, E. Zirngiebl, J. L. Smith, and S.‐W. Cheong (unpublished).
11.
S. Hosoya, M. Onoda, and M. Sato, Jpn. J. Appl. Phys. (to be published).
12.
H. Takagi, S. Uchida, H. Sato, H. Ishii, K. Kishio, K. Kitizawa, K. Fueki, and S. Tanaka, Jpn. J. Appl. Phys. (to be published).
13.
K.
Kitizawa
,
K.
Kishio
,
H.
Takagi
,
T.
Hasegawa
,
S.
Kanabe
,
S.
Uchida
,
S.
Tanaka
, and
K.
Fueki
,
Jpn. J. Appl. Phys.
26
,
339
(
1987
).
Crossref
Search ADS
 
14.
J. J. Neumeier, Y. Dalichaouch, J. M. Ferreira, R. R. Hake, B. W. Lee, M. B. Maple, M. S. Torikachvili, K. N. Yang, and H. Zhou (unpublished).
15.
R. R.
Hake
,
Phys. Rev.
158
,
356
(
1967
).
Crossref
Search ADS
 
16.
Y.
Hidaka
,
Y.
Enomoto
,
M.
Suzuki
,
M.
Oda
, and
T.
Murakami
,
Jpn. J. Appl. Phys.
26
,
377
(
1987
).
Crossref
Search ADS
 
17.
W. J.
Skocpoi
 and
M.
Tinkham
,
Rep. Prog. Phys.
38
,
1049
(
1975
).
Crossref
Search ADS
 
18.
T. P. Orlando, K. A. Delin, S. Foner, E. J. McNiff, J. M. Tarascon, L. H. Greene, W. R. McKinnon, and G. W. Hull (unpublished).
19.
We have measured a sample of YbBa2Cu3O9−δ in fields up to 9 T, this sample also has reasonably sharp transitions in an applied magnetic field with dH0.5/dTc = −(2.7 T/K) and ΔTc = 1.84 K(9.3 K) for H = 0(H = 9 T) (⁠Hn as defined in text and ΔTc as defined in Table I).
20.
N. R.
Werthamer
,
E.
Helfand
, and
P. C.
Hohenberg
,
Phys. Rev.
147
,
362
(
1966
).
21.
K.
Maki
,
Phys. Rev.
148
,
362
(
1966
).
Crossref
Search ADS
 
22.
O/.
Fischer
,
H.
Jones
,
G.
Bongi
,
M.
Sergent
, and
R.
Chevrel
,
J. Phys. C
7
,
L450
(
1974
).
Crossref
Search ADS
 
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1987
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