Pseudogap in a superconducting n-type cuprate: An intrinsic interlayer transport study

Abstract

Interlayer transport in magnetic fields for a superconducting n-type cuprate Sm 2− x Ce x CuO 4− δ is investigated. Bulk single crystals and small 30 nm-high mesa structures, sufficiently thin to be free of recently reported partial epitaxial decomposition problems, are prepared to measure the c-axis resistivity ρ c . In the normal state for both the mesas and the bulk crystals, it is found that the intrinsic longitudinal magnetoresistance (MR) is comprised of fundamental positive MR term in proportion to the square of field strength and negative MR term, which is a characteristic behavior of the pseudogap state reported in p-type cuprates. We find that the negative MR term manifests itself below T* = 38(±2) K. At low temperatures it remains finite below 28(±2) T. These characteristic temperature and field obey the Zeeman energy relationship found in the pseudogap state of Bi 2Sr 2CaCu 2O 8+ δ , strongly suggesting the existence of a pseudogap similar to that of p-type cuprates.