Closing the pseudogap in Bi₂Sr₂CaCu₂O_8+y at high-magnetic fields

From the c-axis interlayer resistivity measurements in a field up to 60 T, we evaluate the pseudogap closing field Hpg at which the low-energy density of state is restored to its ungapped value. We find that Hpg becomes temperature independent at low temperatures, in contrast to the characteristic fields of the superconducting state. The Zeeman energy of Hpg is scaled by the pseudogap temperature, indicating a predominant role of spins over the orbital effects in the formation of the pseudogap. © 2002 Elsevier Science B.V. All rights reserved.