Source Of Magnetism Research Articles

Magnetic property of tellurium-infiltrated Inconel 718: First-principles calculations and experimental validation

The fission product element tellurium in fourth-generation molten salt reactors is the primary cause of cracking in nickel-based high-temperature alloy components. This paper reports the emergence and origin of magnetism in the tellurium-infiltrated Inconel 718. The source of magnetism is identified through first-principles calculations. The accuracy of the theoretical calculations is confirmed by comparative magnetic attraction experiments. It indicates that the primary source of magnetism after tellurium infiltration is the generation of Cr3Te4 but not NiNbTe2. The magnetism generated by Cr3Te4 provides an additional driving force for their clustering distribution. This study facilitates the understanding of the mechanisms behind crack formation in nickel-based alloy components and potential solutions.

Dual nature of magnetism driven by momentum dependent f-d Kondo hybridization

The intricate nature of magnetism in uranium-based Kondo lattices is a consequence of correlations between U-5f and conduction electrons. Previously, the source of magnetism has been ascribed to either Mott physics or Ruderman-Kittel-Kasuya-Yosida interaction, both of which are not fully applicable to uranium-based Kondo lattices. Using linearized quasiparticle self-consistent GW plus dynamical mean-field theory, we demonstrate a crossover from incoherent to coherent f-d Kondo cloud in the paramagnetic phase of UTe2, USbTe and USbSe. As the transition occurs, we observe an augmented f-d coherence and Pauli-like magnetic susceptibility, with a substantial frozen magnetic moment of U-5f persisting. We show that momentum dependent f-d hybridization is responsible for the magnetic moments arising from the renormalized f electrons’ van Hove singularity. Our findings provide a perspective to explain the dual nature of magnetism and the long-range magnetic ordering induced by pressure in UTe2.

Designing ultrathin and long ferromagnetic nanowires array for Tunable-Range Majorana zero mode studies

We have conducted a study that focuses on designing a quasi-1D ultrathin and long ferromagnetic nanowires array with excellent linearity. The purpose of this design is to test the presence of Majorana zero modes in pairs over a long distance and the influence of the lateral interaction. Specifically, we investigate the magnetic properties of a one-unit cell thick MoSX nanowire array, where dopant X (H, C, N, O, and F. etc) is utilized, to assess its suitability for our intended purposes. Our findings reveal that the edge magnetization of the optimized MoSX nanowires is comparable to that of 3d transition metals with the Curie transition temperature surpassing room temperature. Our study indicates that the ferromagnetism of the optimized MoSX nanowires is unlikely to be eliminated when placed on an s-wave superconductor due to lattice mismatch. By conducting comparative case studies of various dopants, we establish a connection between the source of magnetism in the nanowires and internal electric fields, charge perturbation, spin-orbital coupling and p-d hybridization. The strong exchange interaction, robust spin-orbital coupling and large local magnetic moment exhibited by long and ultrathin room-temperature ferromagnetic nanowires open up avenues for diverse topological applications.

Identification pyroclastic flow of magnetic minerals (Holocene volcano): A case study of paleo-volcano Lawu on the south side, Central Java, Indonesia

Indonesia is surrounded by three tectonic plates: the Eurasian, Indo−Australian, and Pacific plates. The plates have caused Indonesia to have many volcanoes, both active and inactive, resting, or no longer active. One of the volcanoes belonging to the formed “Rest” category is the ancient Lawu volcano. The mountain is 10,000 radiocarbon years old or approximately 11,430 ​± ​130 calendar years ago, which is part of the Holocene age. The Lawu volcano erupted on November 28, 1885. This paper discusses the study of magnetic minerals in the case of pyroclastic flows originating from Mount Lawu. The values obtained in magnetic susceptibility are 47.53 ​× ​10−6 ​m3/kg to 79.41 ​× ​10−6 ​m3/kg. The results of this susceptibility measurement indicate the presence of igneous rocks resulting from pyroclastic flow. Furthermore, the vibrating sample magnetometer test showed an S−type (ferromagnetic) hysteresis curve, and the value of Mr/Ms (remanence ratio) define was below 0.5, which realized a multi-domain configuration. This ferromagnetic characteristic is attributed to the iron-based mineral (10.4%–17.1%) from the evaluation of X−Ray Fluorescence. The magnetite mineral confirmed in the X-Ray Diffractometer test is the largest source of magnetism in the sample.

Signs of binary evolution in seven magnetic DA white dwarfs

ABSTRACT We present our findings on the spectral analysis of seven magnetic white dwarfs that were presumed to be double degenerates. We obtained time-resolved spectroscopy at the Gemini Observatory to look for evidence of binarity or fast rotation. We find three of our targets have rotation periods of less than an hour based on the shifting positions of the Zeeman-split H α components: 13, 35, and 39 min, and we find one more target with a approximately an hour long period that is currently unconstrained. We use offset dipole models to determine the inclination, magnetic field strength, and dipole offset of each target. The average surface field strengths of our fast rotators vary by 1–2 MG between different spectra. In all cases, the observed absorption features are too shallow compared to our models. This could be due to extra flux from a companion for our three low-mass targets, but the majority of our sample likely requires an inhomogeneous surface composition. Including an additional magnetic white dwarf with similar properties presented in the literature, we find that five of the eight targets in this sample show field variations on minute/hour time-scales. A crystallization driven dynamo can potentially explain the magnetic fields in three of our targets with masses above 0.7 M⊙, but another mechanism is still needed to explain their rapid rotation. We suggest that rapid rotation or low-masses point to binary evolution as the likely source of magnetism in seven of these eight targets.

Magnetic properties of defect induced β-Ga2O3: A first principles study

Electrical and magnetic properties of gallium vacancy (VGa) as well as 3d transition metal ion doped at gallium site (TMGa) in gallium oxide (β-Ga2O3) has been studied under the frame work of density functional theory. Ga vacancy in β-Ga2O3 shows p-type semiconducting behavior along with a ferromagnetic ordering. Spin-spin interaction study reveals that Fe, Ni and Cu substituted at the gallium site of β-Ga2O3 can induce significant amount of magnetic moment along with a stable ferromagnetic ordering. 2p orbital electrons of oxygen near the vacancy site give raise to the large magnetic moment in the gallium vacancy induced system. In the doped system, the 3d orbital electrons of the dopants are the main source of magnetism and a small contribution come from 2p electrons of oxygen. Bader charge analysis and the band-structure calculations have been carried out for all the systems. Gallium vacancy induced β-Ga2O3 could be a viable material for the spintronics applications.

Monte Carlo study of cuprate superconductors in a four-band model: role of orbital degrees of freedom

Understanding the various competing phases in cuprate superconductors is a long-standing challenging problem. Recent studies have shown that orbital degrees of freedom, both Cu e g orbitals and O p orbitals, are a key ingredient for a unified understanding of cuprate superconductors, including the material dependence. Here we investigate a four-band model derived from the first-principles calculations with the variational Monte Carlo method, which allows us to elucidate competing phases on an equal footing. The obtained results can consistently explain the doping dependence of superconductivity, antiferromagnetic and stripe phases, phase separation in the underdoped region, and also novel magnetism in the heavily-overdoped region. The presence of p orbitals is critical to the charge-stripe features, which induce two types of stripe phases with s)-wave and d-wave bond stripe. On the other hand, the presence of orbital is indispensable to material dependence of the superconducting transition temperature (), and enhances local magnetic moment as a source of novel magnetism in the heavily-overdoped region as well. These findings beyond one-band description could provide a major step toward a full explanation of unconventional normal state and high in cuprate supercondutors.

Magnetic plasmons in plasmonic nanostructures: An overview

The magnetic response of most natural materials, characterized by magnetic permeability, is generally weak. Particularly, in the optical range, the weakness of magnetic effects is directly related to the asymmetry between electric and magnetic charges. Harnessing artificial magnetism started with a pursuit of metamaterial design exhibiting magnetic properties. The first demonstration of artificial magnetism was given by a plasmonic nanostructure called split-ring resonators. Engineered circulating currents form magnetic plasmons, acting as the source of artificial magnetism in response to external electromagnetic excitation. In the past two decades, magnetic plasmons supported by plasmonic nanostructures have become an active topic of study. This Perspective reviews the latest studies on magnetic plasmons in plasmonic nanostructures. A comprehensive summary of various plasmonic nanostructures supporting magnetic plasmons, including split-ring resonators, metal–insulator–metal structures, metallic deep groove arrays, and plasmonic nanoclusters, is presented. Fundamental studies and applications based on magnetic plasmons are discussed. The formidable challenges and the prospects of the future study directions on developing magnetic plasmonic nanostructures are proposed.

First-principles study of magnetic properties of the transition metal ion-doped methylamonium lead bromide

Magnetic properties of 3[Formula: see text] transition metal ion-doped methaylamonium lead bromide (MAPbBr[Formula: see text] have been theoretically studied under the framework of density functional theory. All 3[Formula: see text] transition metal ions are doped at the Pb site of MAPbBr3. Some of the 3[Formula: see text] transition metal ions induced a significant amount of magnetic moment with stable ferromagnetic ordering. 3[Formula: see text] orbital electrons of the dopants are the main source of magnetism in all cases. Total density of state calculations has been performed to understand the magnetic behavior. Local magnetization density for stable ferromagnetic ordered state has been calculated to understand the local origin of the magnetic moment. Also, band structure and Bader charge analysis have been done for stable ferromagnetic ordered materials. Ferromagnetism along with semiconducting behavior makes it a viable material for spintronics applications.

First-principles study of magnetic properties of the cobalt doped silver copper sulfide

First principles calculations in the framework of density functional theory have been carried out to study the electronic and magnetic properties of cobalt (Co) doped silver copper sulfide (AgCuS) system. Cobalt doped at Cu site can induces a significant amount of magnetism in AgCuS. The total and partial density of states reveal that 3d orbital electron of the Co atom is the primary source of magnetism and the rest of magnetic moment comes from the 3d orbital electron of Cu atoms. Spin-spin interaction study suggests a ferromagnetic ordering with Ruderman-Kittel-Kasuya-Yoshida (RKKY) type of exchange interaction. The spin polarized density of states calculation suggest the presence of polarized density of states at the Fermi level which makes the system more interesting as a half-metallic ferromagnetic system.

Intrinsic half-metallic properties of MnHm (M: Fe, V, Co, and Cr) in various space groups: A first-principles study

One of the most important challenges in Nano-scale spintronics is the production of intrinsic two-dimensional ferromagnetic half-metals with large spin gaps and high Curie temperatures. Here, by using firs-principles calculation we predict two-dimensional transition metal hydrides MnHm (M: V, Cr, Fe, and Co) have different magnetic properties in various space groups. Our results show the magnetic ground state of VH3, FeH3 and CoH3 in space group P/4nmm, Cr2H3, Fe2H3 and Co2H3 in space group of P-3 m1 is ferromagnetic while V2H3 and CrH3 in space group of P-3 m1 and P/4nmm respectively, are antiferromagnetic. In particular Co2H3 monolayer is 100% spin polarized intrinsic ferromagnetic half metal with spin gap of 3.2 eV and Cr2H3 can also change to half-metal by doping a small amount of electric charge with a band gap of 4.2 eV. The delocalized and unpaired d electrons around the Fermi level act as the chief source of magnetism and half metallicity. The Curie temperature, calculated utilizing the mean-field approximation, is 485 and 227 K for Co2H3 and Cr2H3 monolayers respectively so it can be concluded that Co2H3 and Cr2H3 monolayers are promising candidates for spintronic applications.

Magnetic Properties of Impact UHPHT Glasses, Melt Rocks, Suevitic Breccia and Target Rocks of the Giant Kara Meteorite Crater (Pay-Khoy, Arctic Seashore, Russia)

The shock waves can strongly change the physical properties of the target rock minerals including their density and magnetism which determine petrochemical properties of impactites finely as a rule are resulted in astroblemes contours on geophysical maps. Following to the aero-magnetic mapping data the non-magnetic sedimentary rocks of the Kara target create a zero and negative magnetic field with an average intensity of -1 nT, against the background the southwestern region of the Kara astrobleme provides the positive magnetic anomalies with an intensity of 1 to 3 nT which are in a good correspondence with the Pay-Khoy ridge structure general orientation. The Kara dome is characterised with an isometric negative anomaly of intensity -5 nT. Here we present the magnetic properties of the different kinds of the Kara impactites including impact ultra-high pressure high temperature (UHPHT) melt glasses, melt rocks and suevitic breccia compare to sedimentary target rocks. The petrophysical measurements presented the specific magnetic susceptibility of the impactites in the range of 8 to 48×10-8 SI units, where the UHPHT glasses have the limits from 9 to 38×10-8 SI units (15×10-8 SI units, in average). The sedimentary target is characterised with essentially lower level of magnetic susceptibility – no higher than 15×10-8 SI units, where limestone has it about zero. Following to the similar level of the iron content within the impactites and target rocks the magnetism of the Kara impact melts is explained rather by changing of magnetic properties by the impact process. One of the possible source of magnetism can be partially an iron-containing matter of the asteroid component in the form of pyrrhotine accompanied with Ni and Co impurities. Also, we cannot exclude partial presence of magnetic iron component directly within the quenched impact glasses including UHPHT variety.

Effect of Mn doping and point vacancy on stability and magnetism of ZnO

Understanding the source of magnetism in Mn doped ZnO (ZnO:Mn) is an active area of research, made difficult experimentally by the challenge of controlling point vacancies in ZnO:Mn. Therefore, the stability and magnetic properties of ZnO:Mn with point vacancies were studied by first-principles calculations based on density functional theory (DFT). Formation energy and magnetic moment calculation results show that Mn prefers to cluster in ZnO:Mn. This clustering can become uniformly distributed through modifications by Zn vacancies (V Zn ) or O vacancies (Vo). Magnetic analysis shows that Mn dopant in Zn site (ZnO:Mn Zn ) coupled with V Zn or interstitial Mn (Mn i ) coupled with V O makes ZnO having long-range ordered ferromagnetism (FM) and an increased Curie temperature ( Tc ) above room-temperature. The ZnO:Mn Zn with V Zn exhibits obvious half-metallic characteristics that are of essential benefit to the design and preparation of a new-type of spin-electron injection source dilute magnetic semiconductor. The magnetic sources of ZnO:Mn Zn with V Zn and Mn i -doped ZnO (ZnO:Mn i ) with V O arise from carrier-mediated magnetic interaction and the double exchange of Mn3d, O2p and Zn4s orbitals, consistent with the theories of average field approximation and the double exchange mechanism.

Crystal Structure and Magnetism of Potassium-Intercalated 2,7-Dimethylnaphthalene

The rich physical properties of metal-intercalated polycyclic aromatic hydrocarbon materials have recently attracted considerable attention. Crystals of potassium-intercalated 2,7-dimethylnaphthalene were synthesized via solid phase reaction. The combination of XRD measurements and first-principles calculations indicated that each unit cell contains two potassium atoms and four organic molecules. Magnetization measurements revealed that the samples show a Curie paramagnetism. Theoretical calculations showed that the intercalated structure becomes metallic and has local magnetic moment. Raman spectroscopy confirmed the migration of electron from potassium 4s to carbon 2p orbital, which is the source of magnetism. Our research on naphthalene derivatives is helpful for expanding the range of novel organic magnetic materials and organic superconducting materials.

Magnetism of strangeness: Silenced histories of landscapes

ABSTRACT Why do certain parts of landscape become places for waste disposal? This simple question seems to be easy to answer given the existence of sophisticated tools for formal modelling of a range of environmental, economic, social, and political variables which are supposed to minimize risk, cost, and disequity. There are, however, more subtle factors that shape waste disposal and its inscription in landscape. Using examples of two Czech landfills and drawing upon my ethnographic research of wastescapes, I examine how history, economic interests, social practices, events, material indeterminacies, and multispecies encounters took part in the transformation of these places into loci of ‘strangeness’. Using a metaphor of magnetism I refocus our attention to a capacity of strange entities such as garbage, rubble, military waste, dead bodies, animal farms, and shooting ranges to attract each other along a spatiotemporal continuum. I argue that strangeness sticks to places and tends to perpetuate itself through a series of ‘magnetic’ relations over time. This magnetism stems from the human propensity to classify and dispose of entities whose open-endedness is dangerous and must be controlled through placement. While this process of placement is often imagined as a management of absence, I point to a dialectical relationship to the opposite category of presence as a critical source of magnetism. Waste management, then, becomes envisioned as part of a more general social process that keeps the world meaningful.

Ab-initio studies of electronic and magnetic properties of titanium doped methylammonium lead halides

Ferromagnetic properties in titanium doped methyl ammonium lead halides (MAPbX3, X = I, Cl, Br) have been analyzed using first principles calculations in the framework of density functional theory. Titanium doped at the Pb site of methyl ammonium lead halides shows n-type semiconducting property along with a significant amount of magnetic moment. The total and partial density of state calculations reveals that d orbital of Ti atom is the main source of magnetism and a small contribution comes from the p orbital of Pb and halide ions. The calculated value of low defect formation energy makes it a suitable material for spintronics applications. Bader charge analysis and band structure calculations have been performed for the pristine and doped systems.

First-principles of Be/Mg/Ca doping and point defects of VZn and Hi in the magnetic and optical properties of ZnO

The effects of Be/Mg/Ca doping and the coexistence of Zn vacancies in the magnetic and optical properties of ZnO have been widely reported, but the previous studies have neglected the influence of the H interstitial on the doping system. The source and mechanism of magnetism caused by O ions in the doping system remain unclear, and no reasonable theoretical explanation has been proposed thus far. As a point defect, Zn vacancies are hard to precisely control in experiments. In view of solving this problem, this study uses the first principles under the framework of density functional theory to investigate the effects of the single doping of Be, Mg, and Ca and the coexistence of Zn vacancies and H interstitial in the magnetic and optical properties of ZnO. Findings indicate that the bulk moduli of all doped systems are reduced with respect to that of the undoped Zn36O36. Apart from the O2− ions, some O1− ions exist in all doping systems. The O1− ions containing itinerant electrons are the main source of O ion magnetism in the doping system. The formation energy of the Zn34MHiO36 (M = Be/Mg/Ca) system is lower than that of the Zn34MO36 (M = Be/Mg/Ca) system. Findings indicate that the doping of the H interstitial can reduce the formation energy of the Zn34MO36 (M = Be/Mg/Ca) system, allowing the system to become even more stable. The Zn34BeHiO36 system has the smallest formation energy. The Zn34BeHiO36, Zn34MgHiO36, and Zn34CaHiO36 systems all exhibit magnetism. The carriers’ activity in the photocatalyst, the visible light effect, the separation and lifetime of the carriers, and the photocatalytic oxidation ability are also considered in this research. Compared with the other configurations, the Zn34MgHiO36 system is more stable than the other systems, and it has a longer electron lifetime, stronger electric dipole moment, more obvious absorption spectral red shift, and stronger reduction ability. Therefore, the Zn34MgHiO36 system is the best choice for photocatalysis in H production. This research offers certain theoretical reference value for the design and preparation of new magneto-optical functional materials.

Effect of different doping ratios of Mo doping and Zn vacancy on magneto-optical properties of ZnO

The source of ZnO magnetism in Mo doping and Zn vacancy is not fully understood. Generalized gradient approximate plane wave ultrasoft pseudopotential method was adopted based on the spin density functional theory to solve this problem. The structural stability and magneto-optical properties of Mo doping and Zn vacancy in co-existing ZnO were calculated using the first principle. The band gap of the doping system is narrower than that of the pure ZnO, and the absorption spectrum showed a red shift in the visible light range of 380–600 nm. The Zn34MoO36 had the strongest absorption spectrum intensity, the most significant red shift phenomenon, the easiest electron and hole separation, and the strongest photocatalytic activity. These features are beneficial to the design and preparation of new photocatalysts. When Mo to Zn vacancy ratio of 2:2, the Zn32Mo2O36 has the strongest magnetic properties, and the electron spin polarization was 100%, which is advantageous for designing and preparing the dilute magnetic semiconductors. The Zn32Mo2O36 has shown room temperature ferromagnetism, and the magnetism of the Zn32Mo2O36 came from the hole produced by Zn vacancy. Double exchange interaction occurred between non-pairing itinerant electron in the O–2P orbit near the Zn vacancy and the spin polarization of electrons in Mo-4d orbitals with the hole as a medium. This is consistent with the mean field approximation and the double exchange mechanism theory.

Enhanced Electronic and Magnetic Properties of Cr- and Mn-Doped GeC Zinc Blende

The electronic and magnetic properties of the doped GeC by Cr and Mn are studied using the Koringa-Kohn-Rostoker (KKR) method combined with the coherent potential approximation (CPA). We have determined the nature of the forbidden band gap and investigated the metallic character when the doping is made by the chromium and the manganese. On the other hand, although the doping is above the percolation threshold, the total magnetic moment for Ge1 − 0.25TM0.25C is 0.491 and 0.67 μB for Cr and Mn, respectively. Besides, the polarization as well as the main responsible source of magnetism in the system is determined. Finally, using the mean field theory, the Curie temperature TC is estimated for different concentrations. It was found that the effect of doping with Mn had a significant impact on TC since it exceeded the room temperature. The findings of this work suggest GeC-based diluted magnetic semiconductors as potential materials for electronics applications.

Room-temperature ferromagnetism in boron-doped oxides: a combined first-principle and experimental study

ABSTRACTThe ferromagnetic properties of boron-doped oxides, namely ZnO, MgO, CdO and TiO2 have been studied using first-principle calculations based on density functional theory. A boron atom, when doped at an anion site, generates a magnetic moment per dopant atom ranging from ∼1 µB in TiO2 to ∼3 µB in ZnO. The source of magnetism in the boron-doped oxides is the 2p-orbital electrons of the dopant atom plus a small contribution coming from the oxygen atoms surrounding the dopant. A spin–spin interaction study reveals that the doping of B at O sites favours ferromagnetic spin coupling in ZnO, MgO, CdO and TiO2. Boron-doped samples have been prepared by ion-beam irradiation with a 10 keV B+ beam implanting on sample pallets. Magnetic measurements have been carried out for B+-ion-implanted oxide samples using a SQUID magnetometer. A stable room-temperature ferromagnetic ordering is observed in boron-ion-irradiated ZnO, MgO, CdO and TiO2 samples.