Spin–spin interactions in defects in solids from mixed all-electron and pseudopotential first-principles calculations

Understanding the quantum dynamics of spin defects and their coherence properties requires an accurate modeling of spin-spin interaction in solids and molecules, for example by using spin Hamiltonians with parameters obtained from first principles calculations. We present a real-space approach based on density functional theory for the calculation of spin-Hamiltonian parameters, where only selected atoms are treated at the all-electron level, while the rest of the system is described with the pseudopotential approximation. Our approach permits calculations for systems containing more than 1000 atoms, as demonstrated for defects in diamond and silicon carbide. We show that only a small number of atoms surrounding the defect needs to be treated at the all-electron level, in order to obtain an overall all-electron accuracy for hyperfine and zero-field splitting tensors. We also present results for coherence times, computed with the cluster correlation expansion method, highlighting the importance of accurate spin-Hamiltonian parameters for quantitative predictions of spin dynamics.

Controlled emission time statistics of a dynamic single-electron transistor

Quantum technologies involving qubit measurements based on electronic interferometers rely critically on accurate single-particle emission. However, achieving precisely timed operations requires exquisite control of the single-particle sources in the time domain. Here, we demonstrate accurate control of the emission time statistics of a dynamic single-electron transistor by measuring the waiting times between emitted electrons. By ramping up the modulation frequency, we controllably drive the system through a crossover from adiabatic to nonadiabatic dynamics, which we visualize by measuring the temporal fluctuations at the single-electron level and explain using detailed theory. Our work paves the way for future technologies based on the ability to control, transmit, and detect single quanta of charge or heat in the form of electrons, photons, or phonons.

Transition Energy, Orientation Force and Work Done in Transitional Behavior Atoms: Formulating New Principles in Thermodynamics

A study of different parameters in thermodynamics is important to describe the science of various physical and chemical phenomena. Solid atoms give birth to condensed matter science when dealing with different transition states at suitable level (of ground surface). A same is the case in atoms of gaseous state but in a different way. In this context, study finds an anomaly associated with the first law of thermodynamics. The anomaly is resolved for the equations of change in the internal energy of a system composed of atoms. To undertake transition state, a gaseous atom involves transitional energy in a gaining manner. Hence, the work is carried out by that gaseous atom. This can be registered symbolically in a plus form. A solid atom involves transitional energy absorbed in undertaking transition state. Hence, the work is carried out on that solid atom, which can be registered in a minus form. In a system composed of gaseous or solid atoms, varying energy and force introduce different transition states. A levitational force exerts at electron level in an atom of gaseous state, whereas a gravitational force exerts at electron level in an atom of solid state. An electron changes potential energy as per the available transition energy for its atom, thereby it controls position by the introduced orientation force while remaining clamped in energy knot. Based on the orientations of electrons, understandable concepts of cooling and heating are deduced from their respective gaseous atoms and solid atoms when recovering from achieved ‘attaining liquid states’.

Atomic-precision engineering of metal nanoclusters

This frontier article illustrates single-atom, single-electron level engineering for tailoring the properties of metal nanoclusters using gold as a model.

Reducing Radiation Damage in Soft Matter with Femtosecond Timed Single-Electron Packets

We study the effects on radiation damage of using a femtosecond laser-driven, pulsed electron source in an otherwise conventional transmission electron microscope. We demonstrate precise control - at the single electron level - over the emission timing and the number of electrons emitted with each femtosecond laser pulse. We find that radiation damage is significantly reduced for such pulsed beams when compared to conventional ultralow-dose methods for the same dose rate and the same total dose. We also show that the degree of damage can be controlled by carefully varying the time between arrival of each electron at the specimen and by changing the number of electrons in each packet.<br>

Reducing Radiation Damage in Soft Matter with Femtosecond Timed Single-Electron Packets

We study the effects on radiation damage of using a femtosecond laser-driven, pulsed electron source in an otherwise conventional transmission electron microscope. We demonstrate precise control - at the single electron level - over the emission timing and the number of electrons emitted with each femtosecond laser pulse. We find that radiation damage is significantly reduced for such pulsed beams when compared to conventional ultralow-dose methods for the same dose rate and the same total dose. We also show that the degree of damage can be controlled by carefully varying the time between arrival of each electron at the specimen and by changing the number of electrons in each packet.<br>

Hard Coating Deposits: Incompatible Working Energy and Forced Behaviors of Gaseous and Solid Atoms

Coating a suitable material on substrate in thickness of nano to micro metres is a great interest for the scientific community. Hard coatings develop under the significant composition of suitable gaseous and solid atoms, where their energy and forced behaviors under certain transition states favour the binding. In the binding mechanism of gaseous and solid atoms, electron belonging to outer ring (filled state) of gaseous atom undertakes another clamp of energy knot belonging to outer ring (unfilled state) of solid atom. The set process conditions develop the coating of gaseous and solid atoms when energy of non-conservation is involved. Different natured atoms develop the structure in the form of hard coating by locating a common ground point, which is in their central ground points. Here, gaseous atoms increase the potential energy of electrons by decreasing levitational force (at electron level) in a controlled orientating manner, whereas solid atoms decrease the potential energy of electrons by decreasing gravitational force (at electron level) in a controlled orientating manner. Thus, hard coating is deposited under the oppositely switched energy and forced behaviors of different natured atoms. In TiN coating, Ti&ndash;Ti atoms bind due to the difference of expansion in their lattices when one atom is deposited and one is being deposited. So, one Ti atom just lands on the already landed Ti atom. While adhering N atom to Ti atom, it occupies the interstitial position in the Ti atoms. The rate of ejecting solid atoms depends on the type of source, parameters and a processing technique. In random arc-based vapor deposition system, depositing coating at substrate depends on several parameters. As per set conditions of the process, different natured atoms deposit at substrate surface to develop the structure of coating. In addition to intrinsic behavior of atoms, different properties of coatings materialised as per the nature of forces engaged under the involved energy. In developing hard coating of gaseous and solid atoms, an involved energy of non-conservation engages force of non-conservation, too. Hence, this study opens new avenues not only in the fields of hard coatings but also in the fields of functional coatings, medical and surgical implant coatings, protective and sensitive coatings, etc.

Reducing Radiation Damage in Soft Matter with Femtosecond Timed Single-Electron Packets

We study the effects on radiation damage of using a femtosecond laser-driven, pulsed electron source in an otherwise conventional transmission electron microscope. We demonstrate precise control - at the single electron level - over the emission timing and the number of electrons emitted with each femtosecond laser pulse. We find that radiation damage is significantly reduced for such pulsed beams when compared to conventional ultralow-dose methods for the same dose rate and the same total dose. We also show that the degree of damage can be controlled by carefully varying the time between arrival of each electron at the specimen and by changing the number of electrons in each packet.<br>

Hard Coating is Because of Oppositely Worked Force-Energy Behaviors of Atoms

Coating of suitable materials having thickness of few atoms to several microns on a substrate is of great interest to the scientific community. Different hard coatings develop under the significant composition of suitably different natured atoms when their force-energy behaviors in certain transition states provide the provision to bind (adhere). In the binding mechanism of different nature suitable atoms, electron (of outer ring) belonging to filled state gas atom takes another clamp of energy knot (of outer ring) belonging to unfilled state solid atom. Set conditions of the process provide the provision of binding different nature atoms in a technique or method meant for it. Different natures of atoms develop structure in the form of hard coating by locating ground points between their original ones where gaseous nature atoms increase potential energy under the decreasing levitational force at electron-level while the solid atoms decrease potential energy under the decreasing gravitational force at electron-level. In TiN coating, Ti&ndash;Ti binding occurs through the difference of expansion of their energy knots nets when one atom just lands on the already landed atom while the adhered nitrogen atom incorporates at their interstitial position. Under suitable set parameters, differently natured atoms deposit in the form of coating at substrate surface under the given conditions. The rate of ejecting or dissociating of solid-natured atoms from the source depend on its nature, process parameters and the processing technique. In random arc-based vapor deposition system, depositing differently natured atoms at substrate surface depends on the input power. In addition to intrinsic nature of atoms, different properties and characteristics of coatings emerge as per engaged forces under the involved energy. The present study sets new trends in the field of coatings involving the diversified class of materials and their counterparts.

Controlling magnetism of Au133(TBBT)52 nanoclusters at single electron level and implication for nonmetal to metal transition

The [Au133(SR)52]q nanocluster is discovered to possess one spin per particle when q = 0, but no unpaired electron when q = +1.