Evidence for universal signatures of zeeman-splitting-limited pseudogaps in superconducting electron- and hole-doped cuprates

Abstract

We probe the normala state in electron-doped (n-type) Sm2-xCexCuO4- through interlayer tunneling transport in magnetic fields up to 45 T. The behavior of intrinsic high-field c-axis negative magnetoresistance (MR), which is accessed in small 30 nm-high mesa structures, is characteristic of the pseudogap state. It follows a universal correlation between the excess low-energy dissipation due to the pseudogap and its closing field Hpg and is in close correspondence with the hole-doped (p-type) Bi2Sr2CaCu2O8+y. The MR in the mesas and in the bulk crystals consistently gives a Zeeman relation between the pseudogap temperature T* and its closing field, pointing to a preeminent role of spin-singlet correlations in forming the pseudogap in cuprates, regardless of their n or p type. © 2005 The American Physical Society.