Nanopore technologies are being developed for fast and direct sequencing of single DNA molecules through detection of ionic current modulations as DNA passes through a pore's constriction 1,2 . Here we demonstrate the ability to resolve changes in current that correspond to a known DNA sequence by combining the high sensitivity of a mutated form of the protein pore Mycobacterium smegmatis porin A (MspA) 3 with phi29 DNA polymerase (DNAP) 4 , which controls the rate of DNA translocation through the pore. As phi29 DNAP synthesizes DNA and functions like a motor to pull a single-stranded template through MspA, we observe well-resolved and reproducible ionic current levels with median durations of ~28 ms and ionic current differences of up to 40 pA. Using six different DNA sequences with readable regions 42-53 nucleotides long, we record current traces that map to the known DNA sequences. With singlenucleotide resolution and DNA translocation control, this system integrates solutions to two longstanding hurdles to nanopore sequencing 2 .In nanopore DNA sequencing, a pore inserted into a membrane permits the flow of ionic current when a voltage is applied across the membrane. As a strand of DNA passes through the pore, it causes changes in current that can be related to the sequence of the DNA. Such a strategy offers the promise of rapidly sequencing long single molecules of DNA 2 , amplification-free sample preparation 1 and direct detection of epigenetic modifications such as base methylation 3,5 . Recent progress toward nanopore sequencing has included determining the resolution and characterizing the recognition sites of biological nanopores MspA 3,6 and α-hemolysin 7-9 as well as developing a method to slow DNA translocation though a nanopore 4,6,10 . However, to our knowledge no system has yet been reported that can read nucleotide-specific current levels as an unmodified strand of DNA passes through a nanopore. In this work, we read DNA by detecting current levels associated with singlenucleotide movement of the strand through MspA. Base-calling algorithms will need to be developed to translate these ionic current reads into a DNA sequence.

As the only non-carbon elemental layered allotrope, few-layer black phosphorus or phosphorene has emerged as a novel two-dimensional (2D) semiconductor with both high bulk mobility and a band gap. Here we report fabrication and transport measurements of phosphorene-hexagonal BN (hBN) heterostructures with one-dimensional (1D) edge contacts. These transistors are stable in ambient conditions for >300 hours, and display ambipolar behavior, a gate-dependent metalinsulator transition, and mobility up to 4000 cm 2 /Vs. At low temperatures, we observe gatetunable Shubnikov de Haas (SdH) magneto-oscillations and Zeeman splitting in magnetic field with an estimated g-factor ~2. The cyclotron mass of few-layer phosphorene holes is determined to increase from 0.25 to 0.31 m e as the Fermi level moves towards the valence band edge. Our results underscore the potential of few-layer phosphorene (FLP) as both a platform for novel 2D physics and an electronic material for semiconductor applications. *

Many physical phenomena can be understood by single-particle physics; that is, treating particles as non-interacting entities. When this fails, many-body interactions lead to spontaneous symmetry breaking and phenomena such as fundamental particles' mass generation, superconductivity and magnetism. Competition between single-particle and many-body physics leads to rich phase diagrams. Here we show that rhombohedral-stacked trilayer graphene offers an exciting platform for studying such interplay, in which we observe a giant intrinsic gap B42 meV that can be partially suppressed by an interlayer potential, a parallel magnetic field or a critical temperature B36 K. Among the proposed correlated phases with spatial uniformity, our results are most consistent with a layer antiferromagnetic state with broken time reversal symmetry. These results reflect the interplay between externally induced and spontaneous symmetry breaking whose relative strengths are tunable by external fields, and provide insight into other low-dimensional systems.

Few-layer black phosphorus acts as tunable ambipolar wide quantum wells.

Few layer phosphorene(FLP) devices are extensively studied due to its unique electronic properties and potential applications on nano-electronics . Here we present magnetotransport studies which reveal electron-electron interactions as the dominant scattering mechanism in hexagonal boron nitride-encapsulated FLP devices. From weak localization measurements, we estimate the electron dephasing length to be 30 to 100 nm at low temperatures, which exhibits a strong dependence on carrier density n and a power-law dependence on temperature (~T -0.4 ).These results establish that the dominant scattering mechanism in FLP is electron-electron interactions.The experimental isolation of graphene on insulating substrates[1] over a decade ago has led to the explosively increasing interest in two-dimensional (2D) materials [2]. A plethora of 2D atomic layers have been investigated, with properties ranging from semi-metallic, metallic, semiconducting, insulating and superconducting, with many fascinating electronic, optical, thermal and mechanical properties.One of the recent additions to the family of 2D materials is phosphorene, which is singleor few-atomic layers of black phosphorus (BP). BP is the most stable form of elemental phosphorus, consisting of layers held together by weak van der Waal's forces. Within each layer, the phosphorus atoms are arranged in a puckered structure [3,4] It has recently piqued the interest of the scientific community due to its high mobility [5], direct band gap that is tunable by thickness or strain [6][7][8][9][10][11][12], and large in-plane anisotropy [4,7,12,13]. These properties make BP a highly attractive candidate for electronics, thermal and optoelectronics applications, as well as a *

Using transport measurements, we investigate multicomponent quantum Hall (QH) ferromagnetism in dual-gated rhombohedral trilayer graphene (r-TLG), in which the real spin, orbital pseudospin and layer pseudospins of the lowest Landau level form spontaneous ordering. We observe intermediate quantum Hall plateaus, indicating a complete lifting of the degeneracy of the zeroth Landau level (LL) in the hole-doped regime. In charge neutral r-TLG, the orbital degeneracy is broken first, and the layer degeneracy is broken last and only the in presence of an interlayer potential U⊥. In the phase space of U⊥ and filling factor ν, we observe an intriguing "hexagon" pattern, which is accounted for by a model based on crossings between symmetry-broken LLs.Keywords: quantum Hall ferromagnetism, graphene, trilayer, rhombohedral stacking, Landau level crossing * Emails: kenosis101@gmail.com, yafisb@gmail.com; lau@physics.ucr.edu In the quantum Hall (QH) regime, when the energies of two or more Landau levels (LLs) are brought to alignment, the spinor language is often used to describe the different degrees of freedom, such as layer and orbital pseudospins, due to their close analogy to the spins in a twodimensional ferromagnet. When these LLs are less than completely full, competition between these degrees of freedom leads to formation of electronic states with spontaneous ordering of pseudospins, much like the spontaneous real spin alignment in a ferromagnet. For this reason, these symmetry-broken QH states are called QH ferromagnets, with real or pseudo-spin orderings that maybe easy-plane, i.e. akin to a XY Heisenberg magnet, or easy-axis, i.e. akin to an Ising ferromagnet. These QH ferromagnetic states provide a rich platform for investigation of the competition among different symmetries, as well as providing insight into the itinerant magnetism in standard magnets.The recent emergence of two-dimensional (2D) graphene provides new playground for multicomponent QH ferromagnetic states and the associated phase transitions 1-6 7-19 20-28 . With the advent of high mobility samples that may be either suspended 29,30 or supported on BN substrates 31,32 , and advanced device geometry such as dual-gates or split top gates [33][34][35] , few-layer graphene provides QH systems with unusual symmetries and unprecedented tunability.In particular, rhombohedral trilayer graphene is such a QH system with very flat bands near the charge neutrality point. Its LL energies are given bywhere N is an integer denoting the LL index, e the electron charge, v F~1 0 6 m/s the Fermi velocity of single layer graphene, γ 1~0 .3 eV the interlayer hopping energy, and h Planck's constant. The degeneracy between the N=0, 1 and 2 LLs, together with the spin and valley degrees of freedom, yield the 12-fold degeneracy of the lowest LL, and give rise to plateaus at filling factors ν=±6, ±10, ±14… Interactions and/or single particle effects lift this 12-fold degeneracy, leading to incompressible QH ferromagnetic states at intermediate fillings 36,37 , with ex...

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