Investigating the enhancement of lung cancer sensing: the effect of edge halogenation in armchair stanene nanoribbons.

In this research, we explore the impact of edge passivation using halogen atoms on armchair stanene nanoribbon (ASNR) for the early detection of lung cancer biomarkers. We employ non-equilibrium green function (NEGF) and density functional theory (DFT) methods to evaluate sensing characteristics. The edges of ASNR are passivated with fluorine, chlorine, bromine, and iodine atoms. Our findings indicate a significant enhancement in sensing performance upon halogenation of ASNR. Notable changes in adsorption energy and current for edge-halogenated ASNR configurations demonstrate improved sensing behavior. Moreover, current curves exhibit greater distinctiveness of halogenated ASNR in comparison to hydrogenated ASNR. The calculations indicate a change in adsorption energy (Eads) of -7.59 eV, -7.6 eV, -8.3 eV, and -8.6 eV for the adsorption by styrene on I-ASnNR, Br-ASnNR, toluene on Cl-ASnNR, and styrene on F-ASnNR, respectively. The corresponding sensitivity improves up to 37.33%, 38.09%, 38.35%, and 45.5%, respectively. These findings highlight that the most significant change occurs with the edge fluorination of ASnNR. Our findings underscore the effectiveness of halogen atom edge passivation in ASNR for heightened sensing performance, making it a promising choice for the development of early-detection lung cancer sensors.

Enhanced sensing performance of armchair stanene nanoribbons for lung cancer early detection using an electric field.

In this study, we analyze the effect of a uniform external electric field on the sensing behavior of armchair stanene nanoribbons (ASnNRs) for early detection of lung cancer biomarkers. The Density functional theory (DFT) and non-equilibrium Green function (NEGF) methods are used to study the sensing behavior. We use Ez = 0.4 V Å-1 and Ez = -0.4 V Å-1 as vertical electric fields and Ey = 0.08 V Å-1 and Ey = -0.08 V Å-1 as transverse electric fields. Our findings demonstrate that applying an electric field in a negative/positive direction considerably increases/decreases the magnitude of the adsorption energy and the transferred charge. In the presence of Ez = 0.4 V Å-1 and Ey = -0.08 V Å-1, a substantial decrease in current was observed. Furthermore, the current curves become more distinguishable compared to the absence of electric fields. The computed results indicate that the negative direction of the applied electric field enhanced the sensitivity and selectivity of ASnNRs for the detection of lung cancer-related biomarkers. The computed results also show that using Ez = -0.4 V Å-1 reduces the adsorption energy to Eads = -8.89 eV and enhances the sensitivity up to 41.83% for styrene detection, demonstrating an improvement in the sensing performance compared to the situation without an electric field. These findings have practical implications, as they can be used to develop highly sensitive early-detection gas sensors, potentially saving human lives.

Early detection of lung cancer biomarkers in exhaled breath by modified armchair stanene nanoribbons.

In this study, we analyze armchair stanene nanoribbons as excellent sensing substances for the early diagnosis of lung cancer using density functional theory and the non-equilibrium Green function. Four modified configurations of surface- and edge-defected armchair stanene nanoribbons were studied to improve the sensing performance. Our probes indicated that the adsorption energy of armchair stanene nanoribbons is at least five times greater than that of other previously reported substances, such as single-wall carbon nanotubes, phosphorene, and silicene. A noticeable reduction in the current was observed, implying the high sensitivity of our sensing configurations. The adsorption energy and current results suggest that configurations with a single vacancy and edge defects improve the sensitivity and selectivity of the system because of their free dangling bonds. The calculated results demonstrate that the both-side edge defected armchair stanene nanoribbons reduce the adsorption energy to -8.35 eV and increase the sensitivity up to 45% for toluene detection. This reduction in adsorption energy and the surge of sensitivity shows ultra-high sensing performance, yielding a more efficient structure for the future design of early-diagnosis lung cancer sensing applications, thus improving lung cancer patients' survival and life expectancy.

Polarized induced phase grating in a quantized four-level graphene monolayer system.

We discuss the electromagnetically induced grating (EIG) and electromagnetically induced phase grating (EIPG) in a four-level quantized graphene monolayer system. By using the density matrix technique and perturbation theory, we first obtain the self-Kerr nonlinear susceptibility of the graphene system; afterwards, we study the amplitude and phase modulations of the probe light. We discovered that the EIG and EIPG can be found by controlling the elliptically polarized coupling fields that interact with the monolayer graphene system. Owing to the phase modulation of the transmitted light beam, we recognized that the probe strength can also additionally switch from zeroth-order to high-order diffraction. Moreover, we found that the diffraction performance of the grating may be adjusted through tuning the polarization of the coupling light.

Detection of extremely large magnetoresistance in a ring-shaped array of magnetic quantum dots with very high performance and controllable parameters.

Using a Green's function method, we study the magnetoresistance (MR) effect in a ring-shaped array of magnetic quantum dots (QDs), with or without magnetic leads, while the magnetic QDs play the role of magnetic layers in conventional multilayer MR devices. Due to the multiple electronic interferences in this proposed ring-shaped structure, it exhibits extremely large MR values, typically up to four million percent (3.9 × 106% in an array that includes 14 QDs), as it tends to be infinite for a system with more dots. Our results show that when the magnetic moment of all QDs is parallel (antiparallel), the charge current through the outgoing lead is maximal (minimal). In addition, the Rashba spin-orbit interaction and the bias voltage are two significant factors that can control the MR values. Besides, by adjusting the magnitude of the magnetic moment of the QDs, the MR effect can be optimized. Finally, it is revealed that the onsite energy of the QDs is an effective parameter for modifying the value and sign of the MR percentage. Consequently, this ring-shaped structure, with controllable parameters and impressive MR percentages, can be an efficient preferred alternative for ordinary layered MR-based devices, for design of the next generation of nanoscale spintronic systems.

Structural, electronic and optical properties of two-dimensional (M2/3Y1/3)2CO2 (M = Mo,W) iMXene.

Two-dimensional (2D) transition metal carbides and nitrides, known as MXenes, are continuously growing in terms of both crystalline and composition varieties. They have received significant attention in science and technology. The new members of MXenes with in-plane ordered double transition metals have been named as iMXenes. In this study, we have investigated the electronic structures and optical properties of 2D (Mo2/3Y1/3)2CO2 and (W2/3Y1/3)2CO2 iMXene monolayers, using a set of density functional theory calculations. We found that the (Mo2/3Y1/3)2CO2 and (W2/3Y1/3)2CO2 2CO2 are semiconductors with indirect bandgaps of 0.477 eV and 0.655 eV, respectively. To investigate the optical properties, we calculated the absorption spectrum and reflectivity percentage of these structures along x and z directions using the real and imaginary parts of the dielectric function. It is observed that the real and imaginary parts of their dielectric functions possess many peaks in the energy region of less than 3.1 eV. Interestingly, they show high absorption in the visible and UV regions, implying the potential applications of these semiconducting iMXenes in solar cells and optical nanodevices.

Transport characteristics and dwell time in a bilayer phosphorene barrier.

In this paper, transport properties, dwell time and electron conductance were theoretically investigated through a rectangular electrostatic potential barrier in bilayer phosphorene and compared the results with monolayer phosphorene and graphene. It has been shown that in bilayer phosphorene, in the presence of an interlayer induced bias, a four-band approximation describes transport process in the system. The results show that interlayer bias parameter drastically affect transport properties. These effects include: (1) appearance of eight transmission and reflection coefficients from a band within the same band and between the two bands; (2) appearance of the anti-Klein tunnelling phenomenon and tuning the bias of system in such a way which is observed in specified biases and removed in other biases; (3) tuning conductance of the system. Results of dwell time in bilayer phosphorene show that this parameter in terms of barrier thickness does not have a strictly ascending behaviour and in limited range of incident energies (incident angles), the dwell time in the barrier reduces significantly which can be exploited in designing switching devices in nano-electronics. We found that increasing the interlayer bias decreases the intrinsic gap of the bilayer phosphorene which enables us to control the electron transmission rate in the system. In addition, our findings also demonstrate that by tuning the interlayer bias, a large electrical conductance can be achieved which can be used in semiconductor technology. Our study could serve as a basis for investigations of the basic physics of tunnelling mechanisms and using bilayer phosphorene as a proper candidate in low dimensional semiconductor industry.

Dwell time, Hartman effect and transport properties in a ferromagnetic phosphorene monolayer.

In this paper, spin-dependent dwell time, spin Hartman effect and spin-dependent conductance were theoretically investigated through a rectangular barrier in the presence of an exchange field by depositing a ferromagnetic insulator on the phosphorene layer in the barrier region. The existence of the spin Hartman effect was shown for all energies (energies lower than barrier height) and all incident angles in phosphorene. We also compared our results of the dwell time in the phosphorene structure with similar research performed on graphene. We reported a significant difference between the tunneling time values of incident quasiparticles with spin-up and spin-down. We found that the barrier was almost transparent for incident quasiparticles with a wide range of incident angles and energies higher than the barrier height in phosphorene. We also found that the maximum spin-dependent transmission probability for energies higher than barrier height does not necessarily occur in the zero incident angle. In addition, we showed that the spin conductance for energies higher (lower) than barrier height fluctuates (decays) in terms of barrier thickness. We discovered that, in contrast to graphene, the Klein paradox does not occur in the normal incident in the phosphorene structure. Furthermore, the results demonstrated the achievement of good total conductance at certain thicknesses of the barrier for energies higher than the barrier height. This study could serve as a basis for investigations of the basic physics of tunneling mechanisms and also for using phosphorene as a spin polarizer in designing nanoelectronic devices.