Doping effect on the anomalous behavior of the Hall effect in electron-doped superconductor Nd2−xCexCuO4+δ

Abstract

Transport properties of Nd 2−x Ce x CuO 4+δ single crystal films (B c, J ab) are investigated in magnetic fields B up to 9T at T =(0.4-4.2)K. An analysis of normal state (at B > B c2 ) Hall coefficient R H n dependence on Ce doping takes us to a conclusion about the existence both of electron-like and hole-like contributions to transport in nominally electron-doped system. In accordance with R H n (x) analysis an anomalous sign reversal of Hall effect in mixed state at B < B c2may be ascribed to a flux-flow regime for two types of carriers with opposite charges.

Upper critical field in electron-doped cuprate superconductor Nd2−xCexCuO4+δ: Two-gap model

“…In contrast to the other two samples we observe here a convex form of H c2 (T) curve at all temperature interval. The data are remarkably well described by the WHH-like equation in accordance with a result of transport measurements [24] that electrons and holes give nearly equal contributions to the conductivity in this sample, i.e. D 1 ∼ = D 2 .…”

“…The experimentally observed ("real") values of H c2 and T c should be the highest ones: for critical fields these are H [24]).…”

“…From an analysis of R H (B) dependences in a mixed state [24] we have obtained that in as grown sample the critical field for electrons is higher than that for holes: H Table 2. been determined (see Table 2). As for equal diffusivities one has T (2) c /T (1) c = H (2) c2 /H (1) c2 , we can constructed not only real WHH curve for electrons but also virtual one for holes (see Fig.5).…”

“…In our previous work [24] we have analyzed the Ce -doping dependence of the normal state Hall coeffient in optimally reduced Nd 2−x Ce x CuO 4+δ /SrTiO 3 single crystal films and, on the grounds of this analysis, we have recruited a two-carrier model for describing of the mixed state Hall coeffcient. We have adopted a semi-phenomenological description of a mixed state Hall effect by flux-flow model of Bardeen and Stephen modified by coexistence of electrons and holes.…”

Anisotropic temperature dependence of normal state resistivity in underdoped region of a layered electron-doped superconductor Nd2–xCexCuO4

“…epitaxial films with = 0.135, 0.145 and 0.15 by pulsed laser deposition[15,16] of two types :1. Orientation of the film (001) -the c-axis of the…”