Negative in-plane and out-of-plane magnetoresistivities in optimally   doped Bi2Sr2Ca0.8Y0.2Cu2O8+d single crystal
  Both the in-plane and out-of-plane magnetoresistivities have been measured in the normal state of an optimally doped Bi2Sr2Ca0.8Y0.2Cu2O8+d single crystal with a magnetic field applied parallel and perpendicular to the CuO2 planes.   Whatever the magnetic field and the current directions are, a negative magnetoresistivity is obtained over a wide range of temperature above the critical temperature Tc. For the in-plane and out-of-plane measurements, the non-dominant orbital contribution to magnetoresistivity suggests the substantial role played by the spin degrees of freedom. 
D. Thopart, A. Wahl, A. Maignan and Ch. Simon