Normal-state transport in electron-dopedLa2−xCexCuO4thin films in magnetic fields up

Abstract

The in-plane normal-state transport properties of electron-doped superconductor ͑La 2−x Ce x ͒CuO 4 ͑LCCO͒ thin films with 0.06ഛ x ഛ 0.17 are studied in magnetic fields up to 40 Tesla. For the whole doping region investigated, the negative magnetoresistivity ͑n-MR͒ is found below certain temperatures, with minimum n-MR near the optimal doping ͑0.10-0.11͒. In the superconducting region ͑x = 0.09-0.17͒, all the LCCO films show crossover from positive MR to n-MR. For x = 0.09, the magnetic field corresponding to the crossover from positive MR to n-MR shows a parabolic behavior with varying temperature. For x = 0.12, second crossing point of ͑B , T͒ curves is observed by tuning the magnetic field.

Transport anomalies and quantum criticality in electron-doped cuprate superconductors

“…First, there are two crossing points in La 2-x Ce x CuO 4 thin films with x=0.12, the first crossing point occurs before entering the normal state, whereas the second crossing point shows up in the regime of n-MR as seen in Fig. 13 [30]. Second, the magnetoresistance isotherms do not always cross at a fixed critical field, e.g.…”

“…The low temperature metal-insulator transitions tuned by different parameters. Temperature dependence of resistivity for (a) different doping Nd 2-x Ce x CuO 4[21], (b) Nd 2-x Ce x CuO 4 films with disorder controlled by annealing process[28], (c) different magnetic field at x = 0.12 La 2-x Ce x CuO 4 film[30], (d) ion-irradiated Nd 2-x Ce x CuO 4 films[31].…”

“…The magnetoresistance isotherms in La 2-x Ce x CuO 4 thin film with x=0.12 (a) and optimal doped Nd 2-x Ce x CuO 4 thin film[30]. (b), respectively.…”

“…The magnetoresistance isotherms in (a) La 2-x Ce x CuO 4[30]and (b) Pr 2-x Ce x CuO 4 thin films[38].…”

“…In EDLT experiments, the correlation length diverges upon approaching the critical carrier concentration rather than the critical magnetic field, which may result in different vz.Sawa et al[44] found that in La 2-x Ce x CuO 4 thin film with x=0.08, the R □ is about 32 kΩ, by 5 times larger than the value of h/(2e) 2 . Jin et al[30] did field and doping dependent resistance measurements on La 2-x Ce x CuO 4 thin films. They found that in slightly overdoped La 2-x Ce x CuO 4 thin film with x = 0.12, the R □ is about 1.43 kΩ and vz = 0.75.…”