Electronic Transport And Mechanical Properties Of Quantum Wire Irradiated Under Electromagnetic Field

The properties of electronic transport and the cohesion force of quantum wires (nanowires) have been intensively concerned. These properties are not only signif-ical basic physical problems but also are of important potential application in the future as the theoretical basis of tomorrow's nanocircuit and nanodevice. Using Landauer-Biittiker transport theory and the scattering matrix method in this thesis we study the electronic transport properties of a curved quantum wire and of a straight quantum wire partly irradiated by an external THz electromagnetic wave, respectively. The cohesion force properties of a metallic nanowire irradiated by electromagnetic wave were also considered. All these studies are within the framework of free electron.The thesis consists of five chapters. In chapter one we briefly recall the history of the development of the theory of electronic transport in mesoscopic physics, review the present research results and discuss the scientific significance of this aspect. In chapter two we study the transport properties of a curved quantum wire, such as the mixture of transverse modes, suppress of conductance, local density, abrupt change of transmission phase and so on. These properties is compared to those of a perfect quantum wire. The conclusions are: 1. the conductance of the system is less 1 conduction quantum than perfect quantum wire in some specified parameter areas; 2. the mode mixture is severe but the conductance is modified little for the small inner curving radius; 3. the local density is analogy to that of a perfect one; 4. the transmission phase has a abrupt TT change when corresponding transmission amplitude tends zero.Chapter three studies the electronic transport properties of a straight quantum wire partly irradiated by an external THz electromagnetic wave. Using time-dependent mode matched scattering matrix method and based on the theory of the interaction between atom and electromagnetic field, we predict the effect that the longitudinal transport of electron is partly blocked by the lateral emitting electromagnetic wave and give detail analysis of the mechanism and the feature of the effect. We conclude that when the frequency of the external field is resonant with the separation of lateral levels of the quantum wire, 1. the area irradiated by the electromagnetic field can give scattering effect and the transmission curve with emit-ting energy of electron shows an abnormal step; 2. the occupation probabilities of the two lateral levels yield spacial Rabi oscillation in irradiated area; 3. the maximum of electron dwell time in the irradiated area is relation to the transmission; 4. the local density of electron in the irradiated area is altered dramatically by the electromagnetic field. In chapter four, using the quantum statistics method we study the cohesion of a metallic nanowire irradiated under electromagnetic wave based on the results in chapter three. We obtain that the cohesion force is effected notably only when the frequency of electromagnetic field is at the vicinity of the energy span of the lateral levels of the nanowire.In chapter five a summary of the work and a outlook of this aspect are given.