Zapf, V. S. and Yeh, N.-C. and Beyer, A. D. and Hughes, C. R. and Mielke, C. H. and Harrison, N. and Park, M. S. and Kim, K. H. and Lee, S.-I. (2005) Dimensionality of superconductivity and vortex dynamics in the infinite-layer cuprate Sr0.9M0.1CuO2 (M=La,Gd). Physical Review B, 71 (13). Art. No. 134526. ISSN 1098-0121 http://resolver.caltech.edu/CaltechAUTHORS:ZAPprb05
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The high magnetic-field phase diagram of the electron-doped infinite layer high-temperature superconducting (high-T-c) compound Sr0.9La0.1CuO2 was probed by means of penetration depth and magnetization measurements in pulsed fields to 60 T. An anisotropy ratio of 8 was detected for the upper critical fields with H parallel (H-c2(ab)) and perpendicular (H-c2(c)) to the CuO2 planes, with H-c2(ab) extrapolating to near the Pauli paramagnetic limit of 160 T. The longer superconducting coherence length than the lattice constant along the c axis indicates that the orbital degrees of freedom of the pairing wave function are three dimensional. By contrast, low-field magnetization and specific heat measurements of Sr0.9Gd0.1CuO2 indicate a coexistence of bulk s-wave superconductivity with large moment Gd paramagnetism close to the CuO2 planes, suggesting a strong confinement of the spin degrees of freedom of the Cooper pair to the CuO2 planes. The region of the magnetic field-temperature phase diagram between H-c2(ab) and the irreversibility line in the magnetization, H-irr(ab), in Sr0.9La0.1CuO2 is anomalously large for an electron-doped high-T-c cuprate. The large reversible region even approaching zero temperature rules out thermal depinning scenarios. The temperature dependence of H-irr(ab) also differs fundamentally from those predicted for the quenched-disorder-induced vortex phase transitions for H parallel to c at low temperatures. Thus, our finding of a strongly suppressed H-irr(ab) relative to H-c2(ab) at low temperatures is suggestive of the existence of additional quantum fluctuations, possibly due to a magnetic-field-induced competing order such as the spin-density wave (SDW).
|Additional Information:||©2005 The American Physical Society. Received 21 April 2004; revised 9 December 2004; published 29 April 2005. This work was supported by the National Science Foundation under Grant No. DMR-0103045 and DMR-0405088, and the National High Magnetic Field Laboratory at Los Alamos, NM. V.Z. acknowledges support by the Caltech Millikan Postdoctoral Fellowship program. http://arxiv.org/abs/cond-mat/0405072|
|Subject Keywords:||antiferromagnetic order, SR0.9LA0.1CUO2, YBA2CU3O7-DELTA, magnetization, compound, oxygen, state, field|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||03 Nov 2005|
|Last Modified:||26 Dec 2012 08:41|
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