Proceedings of the International Conference on Magnetism

J. Phys. Colloques 49 (1988) C8-2087-C8-2092
DOI: 10.1051/jphyscol:19888943

µSR STUDIES OF HIGH T_C SUPERCONDUCTIVITY

Y. J. Uemura¹, B. J. Sternlieb¹, D. E. Cox², V. J. Emery², A. Moodenbaugh², M. Suenaga², J. H. Brewer³, J. F. Carolan³, W. Hardy³, R. Kadono³, J. R. Kempton³, R. F. Kieff³, S. R. Kreitzman³, G. M. Luke³, P. Mulhern³, T. Riseman³, D. L. Williams³, B. X. Yang³, W. J. Kossler⁴, X. H. Yu⁴, H. Schone⁴, C. E. Stronach⁵, J. Gopalakrishnan⁶, M. A. Subramanian⁶, A. W. Sleight⁶, H. Hart⁷, K. W. Lay⁷, H. Takagi⁸, S. Uchida⁸, Y. Hidaka⁹, T. Murakami⁹, S. Etemad¹⁰, P. Barboux¹⁰, D. Keane¹¹, V. Lee¹² et D. C. Johnston<sup>13

1</sup>  Department of Physics, Columbia University, New York, NY 10027, U.S.A.
²  Brookhaven National Laboratory Upton, New York 11973, U.S.A.
³  TRIUMF and Univ. of British Columbia, Vancouver, B.C., V6T 2A3, Canada
⁴  College of William and Mary, Williamsburg, Virginia 23185, U.S.A.
⁵  Virginia State University, Petersburg, Virginia 23803, U.S.A.
⁶  Du Pont Experimental Station, Wilmington, Delaware 19898, U.S.A.
⁷  G.E. Corporate Research and Development, Schenectady, New York 12301, U.S.A.
⁸  University of Tokyo, Hongo, Tokyo 113, Japan
⁹  NTT Optoelectronics laboratory, Tokai, Ibaraki 319-11, Japan
¹⁰  Bell Communications Research, Red Bank, New jersey 07701, U.S.A.
¹¹  IBM T. J. Watson research Center, Yorktown Heights, New York 10598, U.S.A.
¹²  IBM Almaden Research Center, San Jose, California 95120, U.S.A.
¹³  Ames Laboratory (USDOE), Ames, Iowa 50011, U.S.A.

Abstract
Recent progress of our µSR measurements on high-T_C and related systems is presented. Static magnetic order has been found and studied in La₂CuO₄, (La_2-xSr_x)CuO₄, YBa₂Cu₃O_x, YBa₂ (Cu_3-xCo_x) O₇, as well as in Bi₂Sr₂YCu₂O₈. No magnetic order was found in the 3-dimensional systems BaBiO₃, Ba(Pb_0.1Bi_0.9) O₃, and (BaK) BiO₃ above T = 10 K. The anisotropy of the magnetic field penetration depth λ has been observed by using a c-axis alligned sintered pellet specimen of YBa₂Cu₃O₇. The temperature dependence of λ_|| (for c || H_ext) indicates isotropic superconducting energy gap without any anomalies. Based on the muon spin relaxation rate σ observed in (random) pellet specimens of various high-T_C superconductors, we found a linear relation between T_C and σ α 1/λ² α n_s/m*, which suggests a high energy scale of superconducting coupling. Deviations from this linear relation are seen for samples with large carrier concentrations n_s.