Magneto-electronics Properties Of One-dimensional Nanoflake Quantum Dot Arrays And Defective Ti₂CO₂ Nanoribbons

High integration,fast computing speed,and excellent performance are the goals pursued by electronic devices.Due to a variety of factors,traditional silicon devices have gradually become difficult to meet our requirements.Therefore,many researchers are looking for alternative materials for silicon.In this process,graphene,h-BN,Ti2CO2,and other two-dimensional materials have attracted substantial attention due to their structure and excellent performance,but graphene is a zero-band gap semi-metal,and BN monolayer is a wide band gap semiconductor,which limits their practical application.Ti2CO2 is a non-magnetic semiconductor,making it unable to be used as a magnetic device.In this paper,we modulate their properties by tailoring,stitching,edge chemical modification,applying electric field,introducing defects,and use first-principles calculations based on density functional theory to calculate the magnetic electrons of one-dimensional triangular quantum dot arrays and O-line-vacancy Ti2CO2 nanoribbons.The study shows that they hold potential applied for spintronic devices.The main research contents and findings are showed below:We tailor a graphene nanosheet into the triangle-shaped nanoflake and forming four kinds of different one-dimensional quantum dot arrays(1D QDAs)by close proximity to each other,followed by edge oxidation.The edge adsorption energy,phonon spectrum and molecular dynamics simulations confirm that these structures have high stability.Calculations show that such 1D QDAs are very sensitive to geometry and may act as ferromagnetic metals,half-metals and bipolar magnetic semiconductors,or antiferromagnetic metals and semiconductors.In particular,the ferromagnetic half-metal feature appears in the ground state and has a wide band gap,which indicates that they are excellent magnetic materials.The calculated spin transport characteristics indicate that this array-based device has not only a perfect double spin filtering effect,but also excellent double spin diode characteristics and giant magnetoresistive effect(GMR)effect.Therefore,there may possess advantages over graphene nanoribbons.We also use h-BN monolayer,similar to graphene,to yield triangular nanoflakes.Similarly,we can obtain four kinds of one-dimensional BN quantum dot arrays.Structural stability is identified by the binding energy,phonon spectrum and molecular dynamics simulations.Due to the different linking manners,these 1D QDAs exhibit different quantum confinement effects on the electronic and half-metallic properties.For example,in the nonmagnetic state,the different connection arrays feature semiconductors and metals,respectively.In the ferromagnetic state,all of them are good half-metals with a band gap from-0.6 to 5.1 eV,and the difference is almost 10 times.In addition,the electric-magnetic coupling effect shows that applying a lateral electric field can further improve the half-metallicity of 1D QDA by increasing the bandgap.Finally,in order to solve the MXenes semiconductor application in magnetic devices.We construct Ti2CO2 nanoribbons with a linear vacancy of O atoms.Similarly,the stability of the structure is verified by calculating the binding energy,phonon spectrum and molecular dynamics simulations.calculations based on the density functional theory reveals that,in the ground states,Ti2CO2 nanoribbons with linear vacancy at different positions can be ferromagnetic bipolar magnetic semiconductor,half-semiconductor or narrow-gap half-metal.The calculated projected density of states show that:the energy bands near the Fermi level are mainly formed by the d orbital of Ti atoms.More interestingly,linear vacancy at different positions can strongly modulate the mobility of carriers,where the difference as much as three orders magnitude in hole mobility can be observed.Calculations of the spin transport properties show that the device based on such nanoribbons has not only a perfect double spin filtering effect,but also excellent dual spin diode feature.Overall,these results are of great significance for basic scientific research and its potential applications.