Triaxial strain engineering of magnetic phase in phosphorene (original) (raw)
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Strain-induced electronic phase transition in phosphorene: A Green’s function study
Chemical Physics, 2019
In the present paper, we study the impacts of possible uni-, bi-, and tri-axial strains on the electronic band gap of phosphorene using the density of states (DOS) quantity through the Harrison relation. To reach this goal, we use a tight-binding Hamiltonian model and the Green's function method. The findings report that the electronic phase of phosphorene can be adjustable in the presence of strain. The band gap increases (decreases) when applying the tensile uniaxial strains along the {x, y} (z) direction, while it decreases (increases) when the compressive uniaxial ones are applied. Interestingly, due to the inherent highly anisotropic structure of phosphorene, there is a semiconductor-to-metal phase transition along the z direction as the tensile strain is increased. Furthermore, we found that among all possible configurations for uniform biaxial strains, a flat band emerges at ε x = ε y = −15%, which is a quite new outcome. In addition, phosphorene supports different phase transitions when the triaxial strains are applied, introducing new electro-optical features. Hence, these findings can provide insights into the future experimental research and improve the applications of phosphorene in the real industry such as field-effect transistors.
Perturbation-induced magnetic phase transition in bilayer phosphorene
Journal of Applied Physics, 2019
In the present paper, we theoretically study the impacts of “dilute” charged impurity, perpendicular electric field, and the Zeeman magnetic field on the magnetic phase of Bernal bilayer phosphorene (BLP) along both armchair (AC) and zigzag (ZZ) directions. In so doing, we use the tight-binding Hamiltonian model, the Born approximation, and the Green's function approach. Overall, originating from the inherent anisotropic property of phosphorene, we found that the value of susceptibility along the ZZ direction is larger than the AC direction. Also, dilute charged impurity infected BLP suffers from an antiferromagnetic–paramagnetic–ferromagnetic magnetic phase transition depending on the impurity concentration, whereas the susceptibility increases with impurity scattering potential and converges at strong enough potentials. In addition, our results show that applying a perpendicular electric field leads to an antiferromagnetic–paramagnetic–ferromagnetic transition as well. On the ...
Quantum charge and spin pumping in monolayer phosphorene
Physical Review B, 2020
We study quantum-charge and spin-transport properties and the effects of in-plane strain on the charge and spin currents in a phosphorene monolayer using an adiabatic pumping regime. To achieve this goal, we proposed a device with three external ac gate voltages as oscillating potential barriers that are responsible for the generation of dc pumped current. Using exchange magnetic field induced by proximity effect of a ferromagnetic insulator, we determine the conditions in which fully spin-polarized current and pure spin current (with zero charge current) can be obtained. It is shown that the pumped current in the three-barrier case is about two times greater than the pumped current in a two-barrier system. The effect of strain is investigated and it is found that the spin current increases up to two orders of magnitude by applying the uniaxial strain which shows that the proposed device has high sensitivity to strain and could be used as straintronic devices such as strain switches and strain sensors. Also, in the same conditions, the pumped current in phosphorene is two, four, and five orders of magnitude greater than the pumped current in MoS 2 , silicene, and graphene, respectively. These properties show that phosphorene can be considered as a two-dimensional (2D) semiconductor with great potential for the fabrication of novel spintronic and straintronic devices that can overcome some of the limitations exhibited by conventional 2D materials.
Semiconductor to metal transition in bilayer phosphorene under normal compressive strain
Phosphorene, a two-dimensional (2D) analog of black phosphorous, has been a subject of immense interest recently, due to its high carrier mobilities and a tunable bandgap. So far, tunability has been predicted to be obtained with very high compressive/tensile in-plane strains, and vertical electric field, which are difficult to achieve experimentally. Here, we show using density functional theory based calculations the possibility of tuning electronic properties by applying normal compressive strain in bilayer phosphorene. A complete and fully reversible semiconductor to metal transition has been observed at ∼ 13.35% strain, which can be easily realized experimentally. Furthermore, a direct to indirect bandgap transition has also been observed at ∼ 3% strain, which is a signature of unique band-gap modulation pattern in this material. The absence of negative frequencies in phonon spectra as a function of strain demonstrates the structural integrity of the sheets at relatively higher strain range. The carrier mobilities and effective masses also do not change significantly as a function of strain, keeping the transport properties nearly unchanged. This inherent ease of tunability of electronic properties without affecting the excellent transport properties of phosphorene sheets is expected to pave way for further fundamental research leading to phosphorene-based multi-physics devices.
Van Hove singularity and ferromagnetic instability in phosphorene
Physical Review B, 2015
Using Wannier function-based interpolation techniques, we present compelling numerical evidence for the presence of a van Hove singularity at the Γ point near the phosphorene Fermi energy. We show that in proximity of the van Hove singularity the spin susceptibility presents the logarithmic temperature dependence typical of Liftshitz phase transitions. Furthermore, we demonstrate that the critical temperature for the ferromagnetic transition can be greatly increased (up to 0.05 K) if strain along the zigzag ridges is applied. Although the ferromagnetic state would be very difficult to experimentally reach, the logarithmic temperature behaviour of the spin susceptibility due to the van Hove singularity is found to persist at much higher temperatures (up to ∼97 K).
Modulation of electronic and mechanical properties of phosphorene through strain
Physical Review B, 2015
We report a first-principles study on the elastic, vibrational, and electronic properties of the recently synthesized phosphorene. By calculating the Grüneisen parameters, we evaluate the frequency shift of the Raman/infrared active modes via symmetric biaxial strain. We also study a strain-induced semiconductor-metal transition, the gap size, and the effective mass of carriers in various strain configurations. Furthermore, we unfold the emergence of a peculiar Dirac-shaped dispersion for specific strain conditions including the zigzag-oriented tensile strain. The observed linear energy spectrum has distinct velocities corresponding to each of its linear branches and is limited to the Γ − X direction in the first Brillouin zone.
Physical Review B, 2017
We theoretically investigate the unusual features of the magnetotransport in a monolayer phosphorene ferromagnetic/normal/ferromagnetic (F/N/F) hybrid structure. We find that the charge conductance can feature a minimum at parallel (P) configuration and a maximum near the antiparallel (AP) configuration of magnetization in the F/N/F structure with n-doped F and p-doped N regions and also a finite conductance in the AP configuration with the N region of n-type doping. In particular, the proposed structure exhibits giant magnetoresistance, which can be tuned to unity. This perfect switching is found to show strong robustness with respect to increasing the contact length and tuning the chemical potential of the N region with a gate voltage. We also explore the oscillatory behavior of the charge conductance or magnetoresistance in terms of the size of the N region. We further demonstrate the penetration of the spin-transfer torque into the right F region and show that, unlike graphene structure, the spin-transfer torque is very sensitive to the chemical potential of the N region as well as the exchange field of the F region.
We study the effects of the uniaxial tensile strain and shear deformation as well as their combinations on the electronic properties of single-layer black phosphorene. The evolutions of the strain-dependent band gap are obtained using the numerical calculations within the tight-binding (TB) model as well as the first-principles (DFT) simulations and compared with previous findings. The TB-model-based findings show that the band gap of the strain-free phosphorene agrees with the experimental value and linearly depends on both stretching and shearing: increases (decreases) as the stretching increases (decreases), whereas gradually decreases with increasing the shear. A linear dependence is less or more similar as compared to that obtained from the ab initio simulations for shear strain, however disagrees with a non-monotonic behaviour from the DFT-based calculations for tensile strain. Possible reasons for the discrepancy are discussed. In case of a combined deformation, when both str...
Strain and defects engineering of phosphorene
2017 Asian Conference on Energy, Power and Transportation Electrification (ACEPT), 2017
Optical activity is one of the most fascinating fields in current physics. The strong anisotropic feature in monolayer phosphorene leads to the emergence of non-trivial optoelectronic physics. This paper is devoted to a detailed analysis of strain effects on the optical activity of phosphorene ranging from lowoptical-field to high-optical-field. To do so, a numerical study of the two-band tight-binding model is accomplished using the Harrison rule and the linear response theory. Although the transparency of phosphorene confirms at all frequencies independent of the strain modulus and direction, on average, from low-to high-optical-field limit, the polarization of the reflected wave at critical strains becomes circular and the ellipse axis tends to a rotation of 180. It is found that the maximum absorption takes place at high-energy transitions, which quantitatively depends strongly on the strain modulus and direction. Furthermore, a detailed investigation of compressive and tensile strains results in the dominant contribution of the in-plane compressive and out-of-plane tensile strains to the reflected/transmitted light for low-and intermediate-optical-field ranges, whilst both contribute for the high-optical-field limit. However, overall, in-plane compressive and out-of-plane tensile strains come in to play a role in the absorption spectra. Thereby, the quality of the determined reflection, transmission and absorption waves depends on the regarded regime of the optical field, strain modulus, and strain orientation. These findings if sufficient can be performed and/or tuned experimentally, and a vast number of phosphorenebased optoelectronic devices can be achieved.
Tailoring magnetic characteristics of phosphorene by the doping of Ce and Ti: A DFT study
Physica E: Low-dimensional Systems and Nanostructures, 2019
Phosphorene, a two-dimensional elemental material, has attracted increasing attention owing to its fascinating characteristics. All calculations have been performed with the help of density functional theory (DFT) based on generalized gradient approximation method. In this work, we have explored the occurrence of magnetic moments in the non-magnetic phosphorene due to the substitution of Ce and Ti dopants. In the presence of Ce and Ti impurity atoms at up or down (dn) positions along the zigzag direction, phosphorene exhibits unique magnetic characteristics. The substitution of Ce-Ce or Ti-Ti couple in phosphorene has revealed ferromagnetic and half-metallic characteristics, whereas Ce-Ti couple substitution has shown weak magnetic behavior. On the other hand, the substitution of Ce at up and dn positions, neither have shown magnetic nor half metallic behavior. For Ti doping at up and dn positions, both have revealed a ferromagnetic behavior. These findings grant a productive ground for future spintronics applications based on phosphorene.