College Park, Maryland      June 6 - 10 , 2004

M4-A6 (5:30 PM): Field-induced magnetic correlation in high Tc cuprates (Invited)

Kazuyoshi Yamada (Institute for Materials Research, Tohoku University)

We present results of recent neutron scattering experiments on superconducting cuprates under magnetic field and discuss the interplay between magnetic order and high-Tc superconductivity. In hole-doped La2-xSrxCuO4 (LSCO), magnetic field applied perpendicular to the CuO2 planes of LSCO with x = 0.12 and 0.10 and of La2CuO4 with staged excess oxygen ions enhances the incommensurate elastic peak-intensity without changing both incommensurability and onset temperature of field-induced intensities. In these compounds, no static charge stripe order has ever been induced by magnetic field up to ~10 Tesla. On the other hand, for La1.45Nd0.4Sr0.15CuO4 with a static charge stripe order no remarkable field-effect has been observed for incommensurate peaks. Therefore, the field-induced enhancement of spin correlation is only observable in the superconducting samples accompanied by static/quasi-static spin-density-wave without static charge stripes. In the case of electron-doped superconductors, clear field-effects have been observed in the elastic magnetic peak centered at (π, π). In both Nd2-xCexCuO4 and Pr1-x LaCexCuO4 (PLCCO) the field dependence of the induced component shows a peak at H = 5 ~ 6 Tesla. For PLCCO magnetic field affects the onset temperature for the induced magnetic correlation. Similar to the hole-doped case, the field-induced intensity is observable only in the doping region where elastic magnetic peaks are observed in zero field. We compare these results with those observed by impurity-substitution.

Our recent neutron scattering experiments under magnetic field on LSCO and PLCCO have been done in collaboration with M. Fujita, M. Matsuda, S. Katano, T. Suzuki, C.H. Lee, J.M. Tranquada, C.P. Regnault, B. Khaykovich , S. Wakimoto and R.J. Birgeneau.

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