Negative in-plane and out-of-plane magnetoresistivities in an optimally doped Bi2Sr2Ca0.8Y0.2Cu2O8+delta single crystal

Roth the in-plane and out-of-plane magnetoresistivities have been measured in the normal state of an optimally doped Bi2Sr2Ca0.8Y0.2Cu2O8+delta single crystal with a magnetic field applied parallel and perpendicular to the Cu O2 planes. Whatever the magnetic field and the current directions are, a ne gative magnetoresistivity is obtained over a wide range of temperature abov e the critical temperature T-c. For the in-plane and nut-oi-plane measureme nts, the nondominant orbital contribution to magnetoresistivity suggests th e substantial role played by the spin degrees of freedom.