Electrically Tunable Energy Bandgap in Dual-Gated Ultra-Thin Black Phosphorus Field Effect Transistors

The energy bandgap is an intrinsic character of semiconductors, which largely determines their properties. The ability to continuously and reversibly tune the bandgap of a single device during real time operation is of great importance not only to device physics but also to technological applications. Here we demonstrate a widely tunable bandgap of few-layer black phosphorus （BP） by the application of vertical electric field in dual-gated BP field-effect transistors. A total bandgap reduction of 124 meV is observed when the electrical displacement field is increased from 0.10 V/nm to 0.83 V/nm. Our results suggest appealing potential for few-layer BP as a tunable bandgap material in infrared optoelectronies, thermoelectric power generation and thermal imaging.

Energy and Thermodynamics of the Quantum-Corrected Schwarzschild Black Hole

Energy and thermodynamics are investigated in the Schwarzschild black hole spacetime when considering corrections due to quantum vacuum fluctuations. The Einstein and M？ller prescriptions are used to derive the expressions of the energy in the background. The temperature and heat capacity are also derived. The results show that due to the quantum fluctuations in the background of the Schwarzschild black hole, all the energies increase and the Einstein energy differs from M？ller＇s one. Moreover, when increasing the quantum correction factor aa, the difference between Einstein and M？ller energies, the Unruh–Verlinde temperature as well as the heat capacity of the black hole increases while the Hawking temperature remains unchanged.

How Gravitational Effects on the Quantum Vacuum Might Explain Dark Energy and Dark Matter Observations

Following a brief review of the “black hole dark energy radiation” and “gravitized vacuum” references, a novel theory of how gravity might affect the quantum vacuum is proposed. This overarching theory proposes that the gravitational field of a sufficiently concentrated collection of matter and/or energy upregulates the virtual particle activity of the adjacent quantum vacuum, thus its energy density and lensing capacity. In contrast to general relativity, the particle and wave duality of quantum physics is necessary for understanding quantum vacuum gravitational effects. Very recent supporting and pending observational studies are discussed, including the ingenious and extremely sensitive vacuum scale to be deployed for the Archimedes Experiment. Support or falsification of this proposal may be imminent.

Effect of dark energy models on the energy content of charged and rotating black holes

The energy content of the charged-Kerr(CK)spacetime surrounded by dark energy(DE)is investigated using approximate Lie symmetry methods for the differential equations.For this,we consider three different DE scenarios:cosmological constant with an equation of state parameter$ω_(q)=-2/3,quintessence DE with an equation of state parameterω_(c)=-1,and a frustrated network of cosmic strings with an equation of state parameterω_(n)=-1/3.To study the gravitational energy of the CK black hole surrounded by the DE,we explore the symmetries of the 2nd-order perturbed geodesic equations.It is noticed,for all the values ofω,the exact symmetries are recovered as 2nd-order approximate trivial symmetries.These trivial approximate symmetries give the rescaling of arc length parameter s in this spacetime which indicates that the energy in the underlying spacetime has to be rescaled by a factor that depends on the black hole parameters and the DE parameter.This rescaling factor is compared with the factor of the CK spacetime found in[Hussain et al.Gen.Relativ.Gravit.(2009)]and the effects of the DE on it are discussed.It is observed that for all the three values of the equation of state parameterω,the effect of DE results in decreased energy content of the black hole spacetime,regardless of values of the charge Q,spin a and the DE parameterα.This reduction in the energy content due to the involvement of the DE favours the idea of mass reduction of black holes by accretion of DE given by[Babichev et al.Phys.Rev.Lett.(2004)].