Interlayer magnetotransport study in electron-doped Sm2−x Ce x CuO4−δ

Abstract

Vortex and pseudogap states in electron-doped Sm2−xCexCuO4−δ (x ∼ 0.14) are investigated by the interlayer transport in magnetic fields up to 45 T. To extract intrinsic properties, we fabricated small 30 nm-high mesa structures, sufficiently thin to be free of the recently reported partial decomposition problems. On cooling, the c-axis resistivity ρc of the mesa structures reveals a semiconductive upturn above Tc, followed by a sharp superconducting transition at 20 K. When the magnetic fieldH is applied along the c-axis, ρc(T) shows a parallel shift without significant broadening, as also observed in the hole-doped underdoped cuprates. Above the transition we observe negative magnetoresistance (MR), which can be attributed to the field suppression of the pseudogap, whose magnitude is as small as 38 K. Our results in thex ∼ 0.14 samples closely correspond to the interlayer transport behavior in the ‘overdoped’ regime of hole-doped Bi2Sr2 CaCu2 O8+y.