/Tag: Phosphorene

Kondo-semimetal to Fermi-liquid phase crossover in black phosphorus to pressure-induced orbital-nematic gray phosphorus

2018-07-12T16:33:31+00:00 July 12th, 2018|Categories: Publications|Tags: |

Author(s): L. Craco, T. A. da Silva Pereira, S. R. Ferreira, S. S. Carara, and S. LeoniWe perform a comparative study of the electronic structures and electrical resistivity properties of black (A17) and of pressurized gray (A7) phosphorus, showing band-selective Kondoesque electronic reconstruction in these layered p-band phosphorus allotropes. Based on density functional dynamical m…[Phys. Rev. B 98, 035114] Published Thu Jul 12, 2018

Published in: "Physical Review B".

Double carrier transport in electron doped region in black phosphorus FET. (arXiv:1807.02660v1 [cond-mat.mes-hall])

2018-07-10T04:30:18+00:00 July 10th, 2018|Categories: Publications|Tags: , |

The double carrier transport has been observed in thin film black phosphorus (BP) field effect transistor (FET) devices in highly electron doped region. BP thin films with typical thickness of 15 nm were encapsulated by hexagonal boron nitride (h-BN) thin films to avoid degradation by air exposure. Their Hall mobility has reached 5300 cm2/Vs and 5400 cm2/Vs at 4.2 K in the hole and electron doped regions, respectively. The gate voltage dependence of conductivity exhibits an anomalous shoulder structure in electron doped region. In addition, at gate voltages above the shoulder, the magnetoresistance changes to positive, and there appears an additional slow Shubnikov-de Haas oscillation. These results strongly suggest the appearance of the second carriers, which originate from the second subband with localized band edge.

Published : "arXiv Mesoscale and Nanoscale Physics".

Impedimetric phosphorene field-effect transistors for rapid detection of lead ions

2018-07-05T12:33:36+00:00 July 5th, 2018|Categories: Publications|Tags: |

Stimuli-responsive field-effect transistors (FETs) based on 2D nanomaterials have been considered as attractive candidates for sensing applications due to their rapid response, high sensitivity, and real-time monitoring capabilities. Here we report on an impedance spectroscopy technique for FET sensor applications with ultra-high sensitivity and good reproducibility. An alumina-gated FET, using an ultra-thin black phosphorus flake as the channel material, shows significantly improved stability and ultra-high sensitivity to lead ions in water. In addition, the phase angle in the low frequency region was found to change significantly in the presence of lead ion solutions, whereas it was almost unchanged in the high frequency region. The dominant sensing performance was found at low frequency phase spectrum around 50 Hz and a systematic change in the phase angle in different lead ion concentrations was found. Applying the impedance spectroscopy technique to insulator-gated FET sens…

Published in: "Nanotechnology".

An orbitally derived single-atom magnetic memory. (arXiv:1807.01668v1 [cond-mat.mes-hall])

2018-07-05T00:30:20+00:00 July 5th, 2018|Categories: Publications|Tags: |

A single magnetic atom on a surface epitomizes the scaling limit for magnetic information storage. Indeed, recent work has shown that individual atomic spins can exhibit magnetic remanence and be read out with spin-based methods, demonstrating the fundamental requirements for magnetic memory. However, atomic spin memory has been only realized on thin insulating surfaces to date, removing potential tunability via electronic gating or distance-dependent exchange-driven magnetic coupling. Here, we show a novel mechanism for single-atom magnetic information storage based on bistability in the orbital population, or so-called valency, of an individual Co atom on semiconducting black phosphorus (BP). Distance-dependent screening from the BP surface stabilizes the two distinct valencies and enables us to electronically manipulate the relative orbital population, total magnetic moment and spatial charge density of an individual magnetic atom without a spin-dependent readout mechanism. Furthermore, we show that the strongly anisotropic wavefunction can be used to locally tailor the switching dynamics between the two valencies. This orbital memory derives stability from the energetic barrier to atomic relaxation and demonstrates the potential for high-temperature single-atom information storage.

Published : "arXiv Mesoscale and Nanoscale Physics".

Acetone improves the topographical homogeneity of liquid phase exfoliated few-layer black phosphorus flakes

2018-06-29T14:33:26+00:00 June 29th, 2018|Categories: Publications|Tags: |

Liquid phase exfoliation of 2D materials has issues related to the sorption of the solvent, the oxidation of the sample during storage, and the topographical inhomogeneity of the exfoliated material. N-methyl-2-pyrrolidone (NMP), a common solvent for black phosphorus (BP) exfoliation, has additional drawbacks like the formation of by-products during sonication and poor solvent volatility. Here we demonstrate an improvement in the topographical homogeneity (i.e. thickness and lateral dimensions) of NMP-exfoliated BP flakes after resuspension in acetone. The typical size of monolayers and bilayers stabilised in acetone was 99.8 ± 27.4 nm and 159.1 ± 57 nm, respectively. These standard deviations represent a threefold improvement over those of the NMP-exfoliated originals. Phosphorene can also be exfoliated directly in acetone by very long ultrasonication. The product suspension enjoys the same dimensional homogeneity benefits, which confirms that this effect is an intrinsic proper…

Published in: "Nanotechnology".

Non collinear Magnetism and Phonon Dispersion Relation in Vacancy Induced Phosphorene Monolayer. (arXiv:1806.10885v1 [cond-mat.mtrl-sci])

2018-06-29T02:29:23+00:00 June 29th, 2018|Categories: Publications|Tags: , |

We have studied the electronic, magnetic and linear phonon dispersion behavior of Phosphorene monolayer using rst principle based ab initio method. Phosphorene monolayer is a semiconducting system with a dimensional dependent variable range of band gap. Vacancy has been done to study the geometry and physical behavior of the monolayer system. Pristine, vacancy induced monolayer and vacancy induced doped monolayer are included in the calculation. Dopant concentration has been well checked via optimization algorithm to maintain the dilute magnetic semiconducting behavior of the monolayer system. Density of states and partial density of state indicates the contribution of individual orbitals in the system. Band closing nature in observed in vacancy and doped vacancy states indicating closed dense states and metallic behavior of the perturbed phases. Both antiferromagnetic and ferromagnetic ordering is included in our calculation to get a charm of both ordering in the physical properties of the system. Landau energy level distribution is mapped via Fermi surface with linear dispersion relation in terms of phonon vibrational density of states and linear dispersion relations. The results of linear phonon density of states corroborating with electronic density of states.

Published in: "arXiv Material Science".

Chemiluminescence of black phosphorus quantum dots induced by hypochlorite and peroxide

2018-06-26T14:33:18+00:00 June 26th, 2018|Categories: Publications|Tags: |

Chem. Commun., 2018, Accepted ManuscriptDOI: 10.1039/C8CC04513E, CommunicationHoujing Liu, Mingxia Sun, Yingying Su, Dongyan Deng, Jianyu Hu, Yi LvFor the first time, black phosphorus quantum dots (BP QDs) was found to have chemiluminescence (CL) property in the presence of hydrogen peroxide (H2O2) and hypochlorite (ClO-). Excited phosphorus oxides…The content of this RSS Feed (c) The Royal Society of Chemistry

Published in: "Chemical Communications".

Revealing the immune perturbation of black phosphorus nanomaterials to macrophages by understanding the protein corona

2018-06-26T10:34:26+00:00 June 26th, 2018|Categories: Publications|Tags: |

Revealing the immune perturbation of black phosphorus nanomaterials to macrophages by understanding the protein coronaRevealing the immune perturbation of black phosphorus nanomaterials to macrophages by understanding the protein corona, Published online: 26 June 2018; doi:10.1038/s41467-018-04873-7The formation of a protein corona around nanomaterials is known to have significant effects upon materials in biological applications. Here, the authors report on a study into understanding the protein corona formed on black phosphorus and the implications for interactions with macrophages.

Published in: "Nature Communications".

Spin relaxation due to the D’yakonov-Perel’ mechanism in 2D semiconductors with an elliptic band structure. (arXiv:1806.09488v1 [cond-mat.mes-hall])

2018-06-26T04:30:25+00:00 June 26th, 2018|Categories: Publications|Tags: , |

In this letter, we study the relaxation of nonequilibrium homogeneous spin distribution due to the D’yakonov-Perel’ mechanism in two-dimensional (2D) semiconductors with an elliptic band structure. Within the effective-mass approximation, the low-energy band structure is described using anisotropic in-plane effective mass of free carriers. Spin relaxation time of free carriers is calculated theoretically using the time evolution of the density matrix of a polarized spin ensemble in the strong momentum scattering regime. Results are obtained for scattering potential due to both Coulomb interaction and uncharged defects in the sample. We show that the ratio of spin relaxation time in y- and x- directions within the 2D material plane scales as a power of the corresponding effective mass ratio where the exponent depends on the details of the scattering potential. The model is applied to study spin relaxation of electrons in monolayer black phosphorus, which is known to exhibit significant band structure ellipticity. The model can also predict spin relaxation in mechanically strained 2D materials in which elliptic band structure emerges as a consequence of the modification of the lattice constants.

Published : "arXiv Mesoscale and Nanoscale Physics".

Photocatalytic Activity of Phosphorene Derivatives: Coverage, Electronic, Optical and Excitonic properties. (arXiv:1806.09017v1 [cond-mat.mtrl-sci])

2018-06-26T02:29:20+00:00 June 26th, 2018|Categories: Publications|Tags: |

In the context of two-dimensional metal-free photocatalyst, we investigate the electronic, optical and excitonic properties of phosphorene derivatives within first-principles approach. While two-dimensional phosphorene does not catalyze the complete water splitting reactions, O, S, and N coverages improve the situation drastically, and become susceptible to catalyze the complete reaction at certain coverages. We find that for all these dopants, 0.25 — 0.5 ML coverages are thermodynamically more stable, and does not introduce midgap defect states and the composite systems remain semiconducting along with properly aligned valance and conduction bands. Further, within visible light excitation, the optical absorption remain very high 10$^5$ cm$^{-1}$ in these composite systems, and the fundamental optical anisotropy of phosphorene remains intact. We also investigate the effect of layer thickness through bilayer phosphorene with oxygen coverages. Finally we investigate the excitonic properties in these composite materials that are conducive to both redox reactions. The present results will open up new avenues to take advantage of these metal-free phosphorene derivatives toward its outstanding potential in photocatalysis.

Published in: "arXiv Material Science".

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