Field-enhanced diamagnetism in the pseudogap state of the cuprate Bi2Sr2CaCu2O8+δ superconductor in an intense magnetic field -: art. no. 247002

In hole-doped cuprates, Nernst experiments imply that the superconducting state is destroyed by spontaneous creation of vortices which destroy phase coherence. Using torque magnetometry on Bi2Sr2CaCu2O8+delta, we uncover a field-enhanced diamagnetic signal M above the transition temperature T-c that increases with applied field to 32 Tesla and scales just like the Nernst signal. The magnetization results above T-c distinguish M from conventional amplitude fluctuations and strongly support the vortex scenario for the loss of phase coherence at T-c.