Molecular beam epitaxy of ultra-high-quality AlGaAs/GaAs heterostructures: enabling physics in low-dimensional electronic systems. Intrinsic concentration, effective densities of states, and effective mass in silicon. Charge-carrier mobilities in metal halide perovskites: fundamental mechanisms and limits. Electronic Processes in Ionic Crystals (Oxford Univeristy Press, 1940). Lead halide perovskites: crystal-liquid duality, phonon glass electron crystals, and large polaron formation. Contacting organic molecules by metal evaporation. Haick, H., Ambrico, M., Ghabboun, J., Ligonzo, T. The surface electronic structure of 3–5 compounds and the mechanism of Fermi level pinning by oxygen (passivation) and metals (Schottky barriers). Spicer, W., Chye, P., Garner, C., Lindau, I. Highly narrowband perovskite single-crystal photodetectors enabled by surface-charge recombination. Perovskite light-emitting diodes based on spontaneously formed submicrometre-scale structures. High-efficiency solution-processed perovskite solar cells with millimeter-scale grains. Our results lay the foundation for exploring new physics in this class of ‘soft-lattice’ materials. Furthermore, magnetotransport studies reveal a quantum-interference-induced weak localization behaviour with a phase coherence length up to 49 nm at 3.5 K. We report a Hall mobility exceeding 2,000 cm 2 V –1 s –1 at around 80 K, an ultralow bimolecular recombination coefficient of 3.5 × 10 –15 cm 3 s –1 and a photocurrent gain >10 6 in the perovskite thin films. Compared to the deposited contacts, our van der Waals contacts exhibit two to three orders of magnitude lower contact resistance, enabling systematic transport studies in a wide temperature range. Here we report a van der Waals integration approach for creating high-performance contacts on monocrystalline halide perovskite thin films with minimum interfacial damage and an atomically clean interface. However, their charge transport properties remain elusive, plagued by the issues of excessive contact resistance and large hysteresis in ambient conditions. Finally, we present a systematic comparison of the transport properties of single-valley Weyl fermions, 2D massless Dirac fermions, and 3D conventional electrons.Lead halide perovskites have attracted increasing interest for their exciting potential in diverse optoelectronic devices. In addition, we find that the interplay of electron-electron interaction and disorder scattering always dominates the conductivity at low temperatures and leads to a tendency to localization. In the presence of strong intervalley scattering and correlations, we expect a crossover from the weak antilocalization to weak localization. The weak antilocalization always dominates the magnetoconductivity near zero field, thus gives one of the transport signatures for Weyl semimetals. By including the contributions from the weak antilocalization, Berry curvature correction, and Lorentz force, we compare the calculated magnetoconductivity with a recent experiment. For a single valley of Weyl fermions, we find that the magnetoconductivity is negative and proportional to the square root of magnetic field at low temperatures, as a result of the weak antilocalization. Using the Feynman diagram techniques, we derive the finite-temperature conductivity and magnetoconductivity formulas from the quantum interference and electron-electron interaction, for a three-dimensional disordered Weyl semimetal.
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