Electron Impurity Research Articles

Shallow donor states and interlevel transitions in gapped graphene bilayers

Abstract A variational calculation for the energies of the ground and first excited states of a shallow donor impurity in bilayer graphene (BLG) with an open energy gap is presented in this study. It is shown that the binding energies of the lowest states and the distance between them can be tuned in the region of few tens of meV by changing the gap and tight binding parameter γ 1 , which is responsible for the nearest neighboring interlayer coupling. Based on the results obtained, the optical transition of an impurity electron from the ground to the first excited state in BLG is investigated. We find that the oscillator strength of the transition between the lowest energy states 1 S → 2 P x of a shallow donor also depends on the gap and tight binding parameter γ 1 , but is not sensitive to the value of the cutting parameter of the soft Coulomb potential that is proposed. The transitions between shallow impurity levels in BLG can serve as an alternative tunable source of terahertz radiation. The possibility to tune the energy levels of hydrogenic-like impurities can open new ways for either the creation of coherent superpositions of the energy states or the coherent population transfer between them by applying laser pulses.

Optical and electrical transport properties of α-Ga2O3 thin films with electrical compensation of Sn impurities

Polycrystalline α-Ga2O3 thin films containing secondary phase SnO were grown on BaF2 substrates by magnetron sputtering. The impurity tin concentration, electron concentration, and room temperature mobility of the α-Ga2O3 films are 4.5 × 1020 cm−3, 1.5 × 1015 cm−3, and 26.9 cm2 V−1 s−1, respectively, determined by secondary ion mass spectrometry and Hall effect experiments. The mobility vs temperature dependence confirms that the electrons are mainly subject to polar optical phonon scattering and ionized impurity scattering in the temperature range of 160–400 K. Two ionization energies, 29 and 71 meV, were determined for different temperature ranges by logarithmic resistivity vs the reciprocal of temperature, where the former is the shallow donor SnGa formed by the incorporation of tin into gallium sites. The latter is the shallow acceptor VSn–H associated with secondary phase SnO, and it is the electrical compensation of this shallow acceptor that results in the very low carrier concentration of α-Ga2O3 films. The photoluminescence spectrum exhibits 280 and 320 nm UV radiation, where 280 nm is due to the radiation recombination of electrons trapped by the deep donor state (EC−1.1 eV) with holes trapped by the VSn–H complex. In addition, there are several narrow radiation peaks in the visible region, and the energy levels involved in the radiation transitions are determined one by one after excluding the effects of interference and diffraction.

Formation of a combined electron-hole emission state in the LiRbSO4 – Eu phosphor

In the irradiated phosphor 4 LiRbSO Eu , the mechanisms of formation of the induced or combined electron-emitting state at 3.1-2.94 eV were studied using optical and thermal activation spectroscopy methods. It has been shown experimentally that the combined electron-emitting state of the phosphor is formed from the electron states of impurity and intrinsic electron and hole trapping centers of 24Eu SO   and 34 4 SO SO . Electron and hole trapping centers are created by irradiating the phosphor with photons exceeding the width of the forbidden band of the matrix, where free electrons are created in the conduction band and a hole in the valence band. The trapping center is formed by the capture of free electrons by impurities and anionic complexes according to the reaction 3 2 Eu e Eu      ,2 34 4 SO e SO    . In one process with electron centers, holes in the form of 24SO are localized. Thus, impurity and intrinsic 2 4Eu SO   and 34 4 SO SO  electron-hole trapping centers are formed. Similarly, trapping centers are formed as a result of charge transfer from the excited anion of the 24SO complex to the 3Eu  impurities and to the neighboring 2 4 SO anions according to the reaction ( 2 3 O Eu   ) and ( 2 24O SO  ), and localized holes are also formed in one act along with it. Combined electron-emitting states consisting of impurity and intrinsic electron states are excited by photons with energies of ~4.0 eV and ~4.5 eV.

Radiated power and soft x-ray diagnostics in the SMART tokamak.

A multi-energy soft x-ray diagnostic is planned to operate in the small aspect ratio tokamak (SMART), consisting of five cameras: one for core measurements, two for edge, and two for divertors. Each camera is equipped with four absolute extreme ultra-violet diodes, with three of them filtered by Ti and Al foils for C and O line emissions, respectively, and Be foils for temperature measurements. In addition, two spectrometers will be installed with a vertical line of sight for impurity control. This study introduces a synthetic model designed to characterize radiated power and soft x-ray emissions. The developed code extracts the radiated power and Zeff values by leveraging distributions of electron density, temperatures, and impurity concentrations. The investigation is centered on the predicted scenarios of SMART's first phase of operation (Ip = 100kA; Bt = 0.1T), employing a double-null configuration with positive and negative triangularity. The anticipated impurities encompass C (1%) and Fe (0.01%) from the vessel, as well as O and N (0.1%) from air and water. For simplicity, the distribution is assumed to be homogeneous within the plasma, considering different mixtures with Zeff values ranging between 1 and 2. Finally, the model estimates signal strength for the diagnostic design, proving its feasibility.

Review of Extrinsic Factors That Limit the Catalytic Performance of Transition Metal Dichalcogenides (TMDs) in Hydrogen Evolution Reactions (HER)

AbstractTransition metal dichalcogenides (TMDs) have garnered attention as potential catalysts for water splitting owing to their unique structures, diverse electronic properties, and composition from earth‐abundant elements. While certain TMD catalysts, notably MoS2, have shown promising activity for hydrogen evolution reactions (HER), achieving performance comparable to traditional platinum catalysts remains a challenge. While significant effort has been invested into understanding the effect of TMD's structural properties, such as defectiveness and crystalline phases, recent work has emphasized the role of extrinsic factors on HER. This review summarizes the current understanding of the impact of commonly overlooked electrocatalytic effects that exhibit an enhanced importance in TMD‐based HER. By combining recent advances in theoretical modeling and experimental work, we review the dominating effects of extrinsic factors including electronic resistance, interfacial barriers, surface roughness, oxidation, and valence impurities. Our work aims to provide insights into optimizing TMDs as highly efficient catalysts for HER, facilitating future advancements in hydrogen generation technology.

Validating and speeding up x-ray tomographic inversions in tokamak plasmas

X-ray tomography is a precious tool in tokamaks that provides rich information about the core plasma, such as local impurity concentration, electron temperature and density as well as magnetic equilibrium (ME) and magnetohydrodynamic activity. Nevertheless, inferring the local plasma emissivity from a sparse set of line-integrated measurements is an ill-posed problem that requires dedicated regularization and validation methods. Besides, speeding up the inversion algorithm in order to be compatible with real-time control systems is a challenging task with traditional approaches. In this contribution, in a first part we introduce tools aiming at validating and speeding up the x-ray tomographic inversions based on Tikhonov regularization, including ME constraint and parameter optimization, taking the WEST geometry as an example. In a second part, an alternative approach compatible with real-time, based on a set of neural networks is proposed and compared with the Tikhonov approach for an experimental case.

Impact of combined electric and magnetic fields on the physical properties of GaAs variant quantum ring quarter cross-section in presence of an off-center shallow donor impurity

In this study, we explored the complex effects of electric fields in three unique directions and axial magnetic field on a GaAs-Variant Quantum Ring Quarter Cross-Section (VQRQCS), particularly when there is an off-center shallow donor impurity. The investigation explores the impact of these fields on various physical attributes, including electronic energy, binding energy, magnetic shift, Stark shift, average electron impurity distance, and diamagnetic susceptibility. Using effective mass approximation and three-dimensional finite difference methods we solved the Schrodinger equation. Our result shows that the geometric radius of the VQRQCS has an essential impact on electronic energy. Notably, as the radius increases, the electronic energy decreases, regardless of the presence of fields. In particular, we found that magnetic fields amplify the electronic energy of the ground state. The angle of curvature of the nanostructure and the direction of the electric field also play an important role. Additionally, the electron–impurity binding energy decreases with the growth of the nanostructure, with external fields intensifying this effect. The average distance between the electron and the impurity, analyzed in the context of simultaneously applied fields, provides insight into the Coulomb interaction. Diamagnetic susceptibility, measuring the response of a material to an external magnetic field, is studied, indicating opposition to the external field. In summary, this research highlights the nuanced interactions between electric and magnetic fields that determine the properties of a GaAs quantum ring, providing critical insights for quantum ring-based technological advancements.

Synthesis and characterization of absorption-enhanced alumina solid particle materials for direct irradiation solar-thermal conversion

Based on solar-thermal application more than 1000 °C, a novel combination of sol-gel synthesis and stepwise calcination to prepare metal-ion doped alumina composite particles as heat transfer media were proposed, enhancing solar energy absorption and lowering preparation temperature. Investigations focused on the elemental distribution, phase composition, oxidation states, optical properties and thermal stability of the composites, which were doped with Cr, Co, Cu, Fe, and Mn metal ions in a 100:5 M ratio. The first-principles calculations elucidate the mechanism behind the impact of transition metal ions on alumina’s optical properties. Results show that introducing a small quantity of metal atoms results in new impurity energy levels and electron states around EF = 0. Specifically, the band gap energy of Cu- and Mn–Al2O3 decreases from 6.017 eV to 4.464 eV and 2.170 eV, respectively. Correspondingly, the absorptivity of these composite particles increases from around 20 %–76.6 %. And Tauc analysis indicates a decrease in the optical band gap of the particle materials from 5.37 eV to a range of 2.88–4.90 eV. Additionally, doping with Mn, Fe, and Cu accelerates the in-situ formation of α-Al2O3 crystals, with a phase transition temperature below 1000 °C and a crystallinity exceeding 93 %. Thermal stability tests show that the particles are highly stable, exhibiting a mere 0.49 % mass change between 30 °C and 1200 °C. The stepwise inert annealing strategy and metal-iron doping positively influence the optical performance of alumina, synthesizing long-term high-temperature stable alumina ceramic particles with absorptance enhancement and a low α-Al2O3 phase transition temperature. These attributes make a favorable choice for solar-thermal applications in direct irradiation.

Luminescence and Electron–Hole-Trapping Centers in α-Ca2P2O7−Mn

The mechanisms of formation of induced intrinsic and impurity radiative states, which consist of intrinsic and impurity electron–hole-trapping center states in irradiated Ca2P2O7−Mn and Ca2P2O7 phosphates, were investigated using thermoactivation and vacuum-ultraviolet spectroscopy methods. These centers are excited at photon energies of 4.0 eV and 4.5 eV, which are within the matrix’s transparency region. New radiative-induced states at 3.06 eV and 2.92 eV are demonstrated to be generated upon the excitation of anions by photons with energies of 5.0 and 5.64 eV. This process is due to charge transfer from the ion to the impurities, specifically Mn2+(O2−−Mn2+) and the neighboring ion O 2−−(P2O7)4−. Furthermore, upon the excitation of matrix anions with photon energies exceeding the band gap (8.0–8.25 eV), electron-trapping by impurities such as Mn2+ and (P2O7)4− ions results.

Effect of compressive strain on electronic and optical properties of Cr-doped monolayer WS2.

The electronic properties and optical properties of Cr-doped monolayer WS2 under uniaxial compressive deformation have been investigated based on density functional theory. In terms of electronic structure properties, both intrinsic and doped system bandgaps decrease with the increase of compression deformation, and the values of the bandgap under the same compression deformation after Cr doping are reduced compared with the corresponding intrinsic states. When the compressive deformation reaches 10%, both the intrinsic and doped system band gaps are close to zero. New electronic states and impurity energy levels appear in the WS2 system when doped with Cr atoms. For the optical properties, the calculation and analysis of the dielectric function under each deformation regime of monolayer WS2 show that the compression deformation affects the dielectric function, and when the compression deformation is 10%, the un-doped and Cr-doped regimes show a decrease in ε1(ω) compared to the compression deformation of 8%. For each deformation system, the peak reflections occur in the ultraviolet region. Near the position where the second peak of the absorption spectrum appears, it can be seen that the ability of each system to absorb light gradually decreases with the increase of the amount of deformation and appears to be red-shifted to varying degrees. This study follows the initial principles of the density functional theory framework and is based on the CASTEP module of Materials-Studio software GGA and PBE generalizations are used to perform computations such as geometry optimization of the model. We have calculated the energy band structure of monolayer WS2 with intrinsic and compressive deformations of 2% and 4% using PBE and HSE06, respectively. The band gap values calculated using PBE are 1.802 eV, 1.663 eV, and 1.353 eV, respectively, and the band gap values calculated with HSE06 are 2.267 eV, 2.034 eV, 1.751 eV. The results show that the bandgap values calculated by HSE06 are significantly higher than those calculated by PBE, but the bandgap variations calculated by the two methods have the same trend, and the shape characteristics of the energy band structure are also the same. However, it is worth noting that the computation time required for the HSE06 calculation is much longer than that of the PBE, which is far beyond the capability of our computer hardware, and the purpose of this paper is to investigate the change rule of the effect of deformation on the bandgap value, so to save the computational resources, the next calculations are all calculated using the PBE. The Monkhorst-Pack special K-point sampling method is used in the calculations. The cutoff energy for the plane wave expansion is 400 eV, and the K-point grid is assumed to be 5 × 5 × 1. Following geometric optimization, the iterative precision converges to a value of less than 0.03 eV/Å for all atomic forces and at least 1 × 10-5 eV/atom for the total energy of each atom. The vacuum layer's thickness was selected at 20 Å to mitigate the impact of the interlayer contact force.

Nano spinel NiAl2O4: structure, optical and photocatalytic performance evaluation and optimization

Four kinds of spinel NiAl2O4 were synthesized by the polyacrylamide gel method using Al2(SO4)3·18H2O and Al(NO3)3·9H2O as aluminum salts and anhydrous NiSO4 and NiSO4·6H2O as nickel salts. The effects of different aluminum salts and nickel salts on the structure, optical and photocatalytic activity of spinel NiAl2O4 were confirmed by various characterizations. There is no NiO impurity in the spinel NiAl2O4 synthesized with Al2(SO4)3·18H2O as aluminum salt, while NiAl2O4, NiO and C–O functional group coexist in the target product with Al(NO3)3·9H2O as aluminum salt, and C–O functional group and NiO inhibits the photocatalytic activity of the system. Based on photocatalytic experiment, response surface methodology and free radical verification experiment, the influence of experimental parameters including synthesis pathway, initial drug concentration, initial pH and catalyst content on the photocatalytic activity of spinel NiAl2O4 and the main active species involved in the reaction were investigated. The degradation percentage of spinel NiAl2O4 synthesized with Al2(SO4)3·18H2O as aluminum salt and NiSO4·6H2O as nickel salt was 86.3% at the initial concentration of 50 mg l−1, pH = 5.33 and catalyst content of 1 g l−1. The mechanism investigation confirmed that the C–O functional group plays the dual role of impurity level and electron transfer in the degradation of tetracycline hydrochloride by spinel NiAl2O4.

Energy Transfer in the CaSO4−Dy Thermoluminescent Dosimeter from the Excited State of the SO42− Anionic Complex to the Impurities

The creation of a combined radiative state at 2.95–3.1 eV in the phosphor CaSO4−Dy 3+ has been investigated using vacuum ultraviolet and thermoactivation spectroscopy methods. It is shown that the combined radiative electronic state is formed from the radiative electronic states of the impurity electronic trapping centers Dy 2+− SO4− and the intrinsic electronic radiative states SO43−−SO4− during the excitation of the anion complex SO42−, as a result of charge transfer from the excited anion complex O 2−−Dy 3+ to the impurities and the neighboring anion complex O2−− SO42−. In the CaSO4−Dy phosphor, the combined radiative electronic state and impurity emission of Dy 3+, 2.16 eV and 2.56 eV are excited by photons with energies of 3.95–4.0 eV and 4.5–4.6 eV. Energy transfer from the matrix to the Dy 3+ impurities is revealed upon thermal exposure as a result of the ionization of the electronic capture centers of Dy2+ and SO43−.

Extended dissipaton equation of motion for electronic open quantum systems: Application to the Kondo impurity model.

In this paper, we present an extended dissipaton equation of motion for studying the dynamics of electronic impurity systems. Compared with the original theoretical formalism, the quadratic couplings are introduced into the Hamiltonian accounting for the interaction between the impurity and its surrounding environment. By exploiting the quadratic fermionic dissipaton algebra, the proposed extended dissipaton equation of motion offers a powerful tool for studying the dynamical behaviors of electronic impurity systems, particularly in situations where nonequilibrium and strongly correlated effects play significant roles. Numerical demonstrations are carried out to investigate the temperature dependence of the Kondo resonance in the Kondo impurity model.

Observation of nontrivial Zak phase induced topological states in glow discharge plasma

Plasma blackout, which contains ablative impurities, strongly attenuates the signal of the reentry spacecraft. Traditional methods focus on mitigating electron densities and impurities around the antenna, and metamaterial-based electromagnetic methods have yet to be proven experimentally. We simulate the plasma blackout problem using laboratory plasma supported by gas discharge technology. Alumina pillars are embedded in the plasma background to form plasma photonic crystals, while topological phase transitions are achieved by shrinking and expanding pillars within a unit cell. The topological edge states (TESs) that are insensitive to weak impurities in the transport path are verified theoretically and experimentally. We introduce the glide-reflection (GR) symmetry in the nontrivial lattices to obtain the gapless edge states, which are exclusively observed in the acoustic systems. Meanwhile, the Δω of the gapless TES increases with the electron densities, ensuring a wide communication bandwidth. Furthermore, the strong coupling of heterostructure with GR symmetry in plasma photonic crystals is elucidated. Our work not only provides a new approach to the blackout communication problem but can also serve as a nascent experimental platform to investigate topological electromagnetic phenomena.

First-principles-aided evaluation of the Nernst coefficient beyond the constant relaxation time approximation

The solution of the Boltzmann Transport Equation (BTE) under open voltage conditions and in the presence of simultaneously applied magnetic field and temperature gradient results in the so-called Nernst response of the electrons. The calculation of the Nernst coefficient using first-principles calculations as an extension of the BoltzWann code and under Jones–Zener expansion valid for weak magnetic fields has been the subject of our previous work which provided a general framework for the calculation of the Nernst effect but was not able to capture the experimental results due to the constant relaxation time approximation used. In Contrast to the Seebeck coefficient which is not sensitive to the details of the relaxation times, the Nernst coefficient is proportional to the carrier mobility and hence is greatly affected by the relaxation times. In this work, we focus on the inclusion of the energy-dependent electron–phonon and the electron–impurity relaxation times in our formalism. Using the developed formalism, we successfully reproduced the experimental data of several samples. In this paper, we report our results on Ge, Si, and InSb samples. However, the code is not limited to the reported samples and supports a wide range of materials.

Experimental study of the edge radial electric field in different drift configurations and its role in the access to H-mode at ASDEX Upgrade

The formation of the equilibrium radial electric field (Er) has been studied experimentally at ASDEX Upgrade (AUG) in L-modes of “favorable” (ion ∇ B-drift toward primary X-point) and “unfavorable” (ion ∇ B-drift away from primary X-point) drift configurations, in view of its impact on H-mode access, which changes with drift configurations. Edge electron and ion kinetic profiles and impurity velocity and mean-field Er profiles across the separatrix are investigated, employing new and improved measurement techniques. The experimental results are compared to local neoclassical theory as well as to a simple 1D scrape-off layer (SOL) model. It is found that in L-modes of matched heating power and plasma density, the upstream SOL Er and the main ion pressure gradient in the plasma edge are the same for either drift configurations, whereas the Er well in the confined plasma is shallower in unfavorable compared to the favorable drift configuration. The contributions of toroidal and poloidal main ion flows to Er, which are inferred from local neoclassical theory and the experiment, cannot account for these observed differences. Furthermore, it is found that in the L-mode, the intrinsic toroidal edge rotation decreases with increasing collisionality and it is co-current in the banana-plateau regime for all different drift configurations at AUG. This gives rise to a possible interaction of parallel Pfirsch–Schlüter flows in the SOL with the confined plasma. Thus, the different H-mode power threshold for the two drift configurations cannot be explained in the same way at AUG as suggested by LaBombard et al. [Phys. Plasmas 12, 056111 (2005)] for Alcator C-Mod. Finally, comparisons of Er profiles in favorable and unfavorable drift configurations at the respective confinement transitions show that also the Er gradients are all different, which indirectly indicates a different type or strength of the characteristic edge turbulence in the two drift configurations.

Impurity metallic conduction below the critical concentration of metal-insulator transition in FeCo x Si

Analysis on very detailed measurements of resistivity (ρ) and thermoelectric power (S) of magnetic impurity (Co) substituted iron silicide (FeSi) has been presented in this report. The impurity valence electrons of Co dominate the whole physical properties at low temperatures below 35 K, below the critical concentration x c (≈0.02). The negative thermopower and the positive slope in the resistivity at low temperatures are exciting and show that the system is not entirely insulator below the critical concentration of metal–insulator transition (x c ). So, due to the external impurity electrons, the system’s magnetic ground state could change considerably compared to the parent compound FeSi. This report may help unveil the interesting low-temperature transport properties between x = 0 and x = 0.04 (FeCo x Si). Two band model and variable range hopping model were employed to explain the low-temperature electrical and thermal transport properties.

Quantifying superparamagnetic signatures in nanoparticle magnetite: a generalized approach for physically meaningful statistics and synthesis diagnostics.

Magnetization is a common measurable for characterizing bulk, nanoscale, and molecular materials, which can be quantified to high precision as a function of an applied external field. These data provide detailed information about a material's electronic structure, phase purity, and impurities, though interpreting this data can be challenging due to many contributing factors. In sub-single-domain particles of a magnetic material, an inherently time-dependent rotation of the entire particle spin becomes possible. This phenomenon, known as superparamagnetism (SPM), simultaneously represents a very early size-dependent property to be considered, while being one of the least explored in the current quantum materials era. This discrepancy is, at least in part, due to the need for models with less built-in complexity that can facilitate the generation of comparative data. In this work, we map an extensive dataset of variable-size SPM Fe3O4 (magnetite) to an intrinsic statistical model for their field-dependence. By constraining the SPM behavior to a probabilistic model, the data are apportioned to several decorrelated sources. From this, there is strong evidence that standard measures such as saturation magnetization, MS, are poor comparative parameters, being dependent on experimental knowledge and measurement of the magnetic mass. In contrast, parameters of the intrinsic probability distribution, such as the maximum susceptibility, χmax, are far better suited to describe the SPM behavior itself and do not propagate unknown magnetic mass error. By confining the data fitting to intrinsic variables of the model distribution, scaling parameters, and linear contributions, we find greater value in magnetic data, ultimately aiding potential synthesis diagnostics and prediction of new properties and functionality.

Coherent spin dynamics of rare-earth doped crystals in the high-cooperativity regime

Rare-earth doped crystals have long coherence times and the potential to provide quantum interfaces between microwave and optical photons. Such applications benefit from a high cooperativity between the spin ensemble and a microwave cavity---this motivates an increase in the rare-earth ion concentration which in turn impacts the spin coherence lifetime. We measure spin dynamics of two rare-earth spin species, $^{145}\mathrm{Nd}$ and Yb, doped into ${\mathrm{Y}}_{\text{2}}{\mathrm{SiO}}_{\text{5}}$, coupled to a planar microwave resonator in the high-cooperativity regime, in the temperature range $1.2\phantom{\rule{0.16em}{0ex}}\mathrm{K}$ to $14\phantom{\rule{0.16em}{0ex}}\mathrm{mK}$. We identify relevant decoherence mechanisms, including instantaneous diffusion arising from resonant spins and temperature-dependent spectral diffusion from impurity electron and nuclear spins in the environment. We explore two methods to mitigate the effects of spectral diffusion in the Yb system in the low-temperature limit, first, using magnetic fields of up to 1 T to suppress impurity spin dynamics and, second, using transitions with low effective $g$ factors to reduce sensitivity to such dynamics. Finally, we demonstrate how the ``clock transition'' present in the $^{171}\mathrm{Yb}$ system at zero field can be used to increase coherence times up to ${T}_{2}=6(1)\phantom{\rule{0.16em}{0ex}}\mathrm{ms}$.

Quantum oscillations of Kondo screening phases in strong magnetic fields

We generalize the iterative diagonalization procedure adopted in method of numerical renormalization group to analyze the Kondo effect in strong magnetic fields, where the density of states for itinerary electrons at the chemical potential varies discontinuously as the magnetic field changes. We first examine phases of many-body ground states in the presence of single impurity. By investigating change of $z$-component of total spin, $\Delta S_z$, and spin-spin correlation between the impurity and conduction electrons, we find that there are three states competing for the ground state when Zeeman splitting is present. One of the states is doublet in which the impurity spin is unscreened. The other two states are Kondo screening states with $\Delta S_z=1/2$ and $\Delta S_z=1$, in which the impurity spin is partially screened and completely screened respectively. For Kondo systems with two-impurities in strong magnetic fields, we find that the interplay between the Kondo screening effect, RKKY interaction, and quantum oscillations due to Landau levels determines the ground state of the system. Combination of these three factors results in different screening scenarios for different phases in which spins of two impurities can form spin-0 or spin-1 states, while impurity spins in these phases can be either screened, partially screened, or unscreened by conduction electrons. The emergence of the ground state from these competing states oscillates with the change of magnetic field, chemical potential or inter-impurity distance. This leads to quantum oscillations in magnetization and conductivity. In particular, we find extra peak structures in longitudinal conductivity that reflect changes of Kondo screening phases and are important features to be observed in experiments. Our results provide a complete characterization of phases for Kondo effect in strong magnetic fields.