Magnetic-field-induced Stoner transition in a dilute quantum Hall system

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Metal-to-insulator crossover and pseudogap in single-layer compound Bi2+x_{2+x}Sr2−x_{2-x}Cu1+y_{1+y}O6+delta_{6+\\delta} single crystals in high magnetic fields

11 pages, 8 figuresThe in-plane $\\rho_{ab}(H)$ and the out-of-plane $\\rho_c(H)$ magneto-transport in magnetic fields up to 28 T has been investigated in a series of high quality, single crystal, hole-doped La-free Bi2201 cuprates for a wide doping range and over a wide range of temperatures down to 40 mK. With decreasing hole concentration going from the overdoped (p=0.2) to the underdoped (p=0.12) regimes, a crossover from a metallic to and insulating behavior of $\\rho_{ab}(T)$ is observed in the low temperature normal state, resulting in a disorder induced metal insulator transition. In the zero temperature limit, the normal state ratio $\\rho_c(H)/\\rho_{ab}(H)$ of the heavily underdoped samples in pure Bi2201 shows an anisotropic 3D behavior, in striking contrast with that observed in La-doped Bi2201 and LSCO systems. Our data strongly support that that the negative out-of-plane magnetoresistance is largely governed by interlayer conduction of quasiparticles in the superconducting state, accompanied by a small contribution of normal state transport associated with the field dependent pseudogap. Both in the optimal and overdoped regimes, the semiconducting behavior of $\\rho_c(H)$ persists even for magnetic fields above the pseudogap closing field $H_{pg}$. The method suggested by Shibauchi \\textit{et al.} (Phys. Rev. Lett. \\textbf{86}, 5763, (2001)) for evaluating $H_{pg}$ is unsuccessful for both under- and overdoped Bi2201 samples. Our findings suggest that the normal state pseudogap is not always a precursor of superconductivity

Magnetotransport in Two-Dimensional Electron Gas in Helical Nanomembranes

International audienceHeterostructures containing high-mobility two-dimensional electron gas were rolled into freestanding helically shaped contacted Hall bars. Magnetotransport measurements in these structures at high magnetic fields revealed minima in the longitudinal magnetoresistance corresponding to integer and fractional filling factors. A strong asymmetry of the longitudinal magnetoresistance with respect to the external magnetic field direction was observed. For this new type of structures, an edge state picture was considered, and calculations based on the Landauer–Büttiker formalism are performed

Gap like structure in a nonsuperconducting layered oxycarbonate Bi2+xSr4−xCu2CO3O8+δ single crystal

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Magnetic field dependence of the superconducting energy gap in Bi 2 Sr 2 CaCu 2 O 8 + δ probed using break-junction tunneling spectroscopy

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Gap like structure in a nonsuperconducting layered oxycarbonate Bi2+xSr4−xCu2CO3O8+δ single crystal

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The contact hyperfine interaction and the integer and fractional quantumHall effects

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Temperature dependence of the upper critical field of FeSe single crystals

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Revealing Large-Scale Homogeneity and Trace Impurity Sensitivity of GaAs Nanoscale Membranes

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Using the de Haas–van Alphen Effect to Map Out the Closed Three-Dimensional Fermi Surface of Natural Graphite

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