Hofer J, Conder K, Sasagawa T, Zhao Gm, Willemin M, Keller H, Kishio K
Physik-Institut der Universitat Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
Phys Rev Lett. 2000 May 1;84(18):4192-5. doi: 10.1103/PhysRevLett.84.4192.
We report measurements of the oxygen-isotope effect (OIE) on the in-plane penetration depth lambda(ab)(0) in underdoped La2-xSrxCuO4 single crystals. A highly sensitive magnetic torque sensor with a resolution of Deltatau approximately 10(-12) N m was used for the magnetic measurements on microcrystals with a mass of approximately 10 &mgr;g. The OIE on lambda(-2)(ab)(0) is found to be -10(2)% for x = 0.080 and -8(1)% for x = 0.086. It arises mainly from the oxygen-mass dependence of the in-plane effective mass m(*)(ab). The present results suggest that lattice vibrations are important for the occurrence of high temperature superconductivity.
