Effective Magnetic Moment Research Articles

Intermediate-spin state of Co ions in magnetic and thermoelectric properties of double perovskite Ba2CoNbO6

Double perovskite Ba2CoNbO6, obtained by pyrolysis of nitrate-organic mixtures, was studied by XRD, XRF, DFT, AC/DC-magnetization, specific-heat, thermoelectric, and ESR methods. The sample has cubic symmetry space group Pm3m with a = b = c = 4.0074(11) Å. Deficiency in oxygen ions shows the presence of Co ions in both 3+ and 2+ valency. According to AC-magnetization and specific-heat data, Ba2CoNbO6 demonstrates spin-glass ordering at TSG = 30 K at external field value of 0.1 kOe. This temperature of spin glass transition drops with field power increase down to complete suppression at 10 kOe. The effective magnetic moment determined using the Curie-Weiss approximation is 4.29 μB, which is consistent with the theoretical estimation for Co ions in the intermediate-spin state. The peak at T = 90 K, observed in the temperature dependence of the specific heat and accompanied by a peak in the ESR linewidth, is possibly due to the structural transition at this temperature. The Seebeck coefficient of the compound is S = 4–6.5 μV/K and the band gap obtained within the small-polaron-jump conductivity model is ΔE = 0.284 eV in the temperature range of 350–550 K connected with DFT calculation. An intensity ESR line, related to Co2+ ions, was observed in ESR spectra.

Electrical resistivity and magnetic susceptibility of Al-Ni-Co-Cu-Zr high-entropy alloys in solid and liquid states

Electrical resistivity and magnetic susceptibility of Al-Ni-Co-Cu-Zr alloys with different component ratios are studied in a wide temperature range including both solid and liquid states. The abnormal behavior of properties is discovered in the temperature range 700–1200 K. The increase of magnetic atoms concentration (mainly cobalt) in the alloys composition leads to increase of properties anomalies. Some parameters of the electronic structure - paramagnetic Curie temperature, effective magnetic moment and density of electron states at Fermi level - are calculated from the experimental data.

Synthesis and Characterization of New Copper(II) Coordination Compounds with Methylammonium Cations

We synthesized four new copper(II) complexes with acetato and chlorido ligands and methylammonium (MA), dimethylammonium (DMA), and tetramethylammonium (TMA) counterions: (MA)4[Cu2Ac4Cl2]Cl2·2H2O (1), (DMA)2[Cu2Ac4Cl2] (2), (DMA)4[Cu2Ac4Cl2]Cl2·2H2O (3), and (TMA)5[Cu2Ac4Cl]Cl4·4H2O (4). All compounds were characterized by single-crystal X-ray diffraction, magnetic measurements, FTIR spectroscopy, and thermogravimetric analysis. Complexes 1, 2, and 3 consist of a dinuclear coordination anion [Cu2(Ac)4Cl2]2− with bridging acetato ligands arranged in a paddle-wheel conformation and square-pyramidal coordination around Cu(II) atoms, while the coordination anion in compound 4 is a polymeric chain, parallel to the c axis, with Cu2(Ac)4 units connected through bridging chlorido ligands. Magnetic measurements carried out between 2 K and 300 K indicate strong antiferromagnetic interactions between Cu(II) ions. The effective magnetic moments range from 1.94 μB to 2.21 μB, exceeding the spin-only value for Cu(II) ions (μeff=1.73 μB) and suggesting significant orbital contributions to the magnetic moment. Thermogravimetric analysis of all complexes showed a multistep decomposition behavior yielding elemental copper as the final product.

Mechanism Behind the Enhanced Ferromagnetic Contributions Upon Ru Substitution in Ca3Mn2O7 from X-Ray Absorption Spectroscopies.

We have studied the local structure and electronic and magnetic properties of hybrid improper ferroelectric Ca3Mn2O7 upon Ru substitution at the Mn site by a combination of atomic-selective X-ray absorption spectroscopies in the soft and hard X-ray energy regimes. Ru substitution enhances the macroscopic ferromagnetic contributions, whose origin is here elucidated. In particular, soft X-ray magnetic circular dichroism (XMCD) data indicate that the spin moments of Mn and Ru are aligned in opposite directions, with the effective magnetic moments of Ru being about 1 order of magnitude smaller than for Mn. The XMCD results also demonstrate the presence of an intrinsic ferromagnetic component in the Mn sublattice for Ru contents x ≥ 0.3, although the values of the net Mn magnetic moment are much smaller than expected for a fully saturated Mn4+ magnetic sublattice. Soft and hard X-ray absorption spectroscopy measurements show that Mn keeps a +4 valence state independently of the Ru content, whereas Ru is in an intermediate valence state, ranging between +4.7 (x ≤ 0.1) and +4.4 (x ≥ 0.7). Analysis of the extended X-ray absorption fine structure (EXAFS) signals at the Mn and Ru K-edges suggests the lack of a complete solid solution in the local structure across the entire range of compositions. These findings disclose the existence of charge transfer between Mn and Ru atoms, so the weak ferromagnetic component is attributed to a canting of the antiferromagnetically ordered Mn4+ spins caused by the oxygen-mediated hybridization between localized Mn4+ 3d and itinerant intermediate valence Ru 4d bands, in analogy to the mechanism proposed for ferromagnetism in ordered doubled perovskites with 3d and 4d/5d transition-metal ions. In the present case, disorder prevents the formation of long-range ferromagnetism.

Crystal and thermodynamic properties of [formula omitted], (X = Al, Ga)

The crystal and thermodynamic properties of Tb2Ni2X (X = Al, Ga) are reported through measurements of X-ray diffraction (XRD), magnetic susceptibility, χ(T), magnetization, M(μ0H) and heat capacity, Cp(T). XRD pattern analysis confirms the orthorhombic W2CoB2-type structure with the space group of Immm. χ(T) at high temperature for both compounds follows the Curie – Weiss relationship giving an effective magnetic moment close to that expected for the trivalent Tb ion. The low-temperature χ(Cp) data indicate that both compounds order antiferromagnetically at TN = 41 K (40.4 K) and 41.5 K (41.4 K) for Al and Ga compounds, respectively. Cp(T) data of the nonmagnetic counterparts Y2Ni2X (X = Al, Ga) are well described by the Debye model giving a Debye temperature, θD = 236.9(4) K and 225.3(2) K for Al and Ga compounds, respectively. The low-temperature part of the 4f-magnetic contribution to the total heat capacity, C4f(T) can be described by the antiferromagnetic spin-wave dispersion, giving an energy gap Δsw = 47(3) K and 26(2) K for Al and Ga compounds, respectively. The 4f – magnetic entropy S4f(T) for both compounds reaches the value of 2Rln(2) close to their respective TN values.

Giant effective magnetic moments of chiral phonons from orbit-lattice coupling

Giant effective magnetic moments of chiral phonons from orbit-lattice coupling

Tuning Magnetic and Semiconducting Properties of Cr-Doped CaTiO3 Perovskites for Advanced Spintronic Applications

The physical properties of perovskite-type materials are sensitive to their chemical composition and crystallographic structure, which makes them highly versatile for various advanced technological applications. In this theoretical study, density functional theory (DFT) is employed to investigate the electronic properties of the perovskite-like material CaTiO3, focusing on the substitution of Ti4+ with the magnetic transition metal Cr4+. The results reveal a systematic increase in the effective magnetic moment and a gradual decrease in the bandgap with increasing Cr4+ content in the CaTi1−xCrxO3 system (x = 0.0, 0.25, 0.5, 0.75, 1.0). The interactions between electronic orbitals associated with Ti-O-Cr inter-octahedral bonds modify the magnetic response of the material, leading to hybridizations between valence and conduction states that alter its semiconductor character. This tunability in electronic and magnetic properties underscores the potential of these materials for applications in spintronics. This study offers novel insights into the design of new magnetic semiconductor materials with tailored functionalities, contributing to the development of next-generation spintronic devices.

Effective magnetic moment modulated perovskite-type oxides towards peroxymonosulfate activation: A high-valent metal species and superoxide radical step-by-step oxidation route

Perovskite oxides are considered as promising catalysts in activating peroxymonosulfate (PMS) for environmental remediation, but the intrinsic properties that govern the activity of perovskites are ambiguous. Herein, a series of perovskite-type oxides La2MeO4 (LMe, where Me = Co, Mn, Cu, and Fe) were reported to activate PMS for improving organic pollutant degradation, while the LCo/PMS system showed impressive performance, achieving over 90 % removal of organic contaminants (dyes and antibiotics) under the optimized conditions of 0.05 g/L catalyst and 0.50 mM PMS. Experiments and characterizations verified a good linear correlation between the catalytic activity and effective magnetic moment (μeff) of catalysts, underlining the key role of the spin state of the metal center in governing the intrinsic activity. Additionally, two stages of oxidation pathways were evidenced to be involved in the reaction: i) high-valent cobalt-oxo species (i.e., Co(IV)) were produced from the surface reactive complexes catalyst-PMS*, afterwards ii) a portion of superoxide radicals (O2•−) were formed via the PMS reaction with Co(IV). Overall, these findings provide new insights into the mechanism of the perovskite-activated PMS system for efficient water remediation.

Effect of Deformation on the Magnetic Properties of CrMnFeCoNi and CrMnFeCoNi-CN High-Entropy Alloys

The magnetic behavior of two high-entropy alloys, CrMnFeCoNi and CrMnFeCoNi-CN, was investigated under varying degrees of deformation through uniaxial tensile tests. Microstructural, morphological, and crystalline structural analyses using XRD and SEM revealed a uniform and stable austenitic structure in all samples, with no presence of α’-martensite or ε-martensite phases. The main deformation mechanisms identified were twinning and slip dislocation for the CrMnFeCoNi-CN alloy, and slip dislocation for the CrMnFeCoNi alloy at room temperature. The alloys exhibited low magnetic moments attributed to magnetically frustrated configurations. At temperatures below 70 K, distinct magnetic states were observed ranging from paramagnetic to ferrimagnetic and spin-glass-like behavior. Antiferromagnetic interactions were confirmed by a negative paramagnetic Curie temperature for both alloys. The magnetization of the CrMnFeCoNi alloy increased with deformation, reflected in effective magnetic moments varying from 1.81 (0 pct) to 2.60 (20 pct) μB, while for the CrMnFeCoNi-CN alloy remained stable around 2.39 to 2.48 μB. The magnetization of the CrMnFeCoNi-CN alloy was found to be higher than that of the CrMnFeCoNi alloy, suggesting that the presence of C and N as alloying elements can enhance magnetization to some extent.

Enhanced orbital magnetic moment in an FeCo-BaF2 granular film revealed by x-ray magnetic circular dichroism

FeCo-insulator fluoride nanogranular films belong to an excellent material group that exhibits a huge Faraday effect, which is several times larger than those of conventional materials, in the optical communication wavelength band (1310 ∼ 1550 nm). In this study, FeCo-BaF2 granular films were prepared on glass substrates by a tandem sputtering method. The Faraday effect was measured and a huge Faraday rotation angle of −2.3 deg./μm was observed for the wavelength of 1550 nm. The ratio of orbital magnetic moment to effective spin magnetic moment (morb/mspineff) was evaluated by x-ray magnetic circular dichroism (XMCD) measurements, and was found to be 0.43 for Fe and 0.24 for Co. The obtained values are several times larger than those of Fe-Co bulk samples. The elemental selectivity of the XMCD measurements reveals that Fe has a larger morb/mspineff value than that of Co. Such an increase in morb is attributed to the reduction of the symmetry at the interface between FeCo and BaF2 in the granular film, and is thought to be the origin of the giant Faraday effect in FeCo-fluoride granular films.

Exploring the structural, magnetic and shielding performance of Mn doped Yb2O3 and Eu2O3 nanostructures

Re2-xMnxO3 (ReYb or Eu, x = 0.0, 0.05, 0.1, 0.15) nanostructures were produced utilizing the sol-gel procedure. The crystal structure and microstructure of all samples were analyzed based on XRD measurements using the Rietveld profile approach. The lattice parameter, cation distribution of different cations between different crystallographic sites, bond lengths of different polyhedrons, crystallite size, micro-strain and distortion index of the different polyhedrons of the formed sample were determined. Mn cations were found to prefer the 8b sites of the cubic bixbyite structure. The average crystallite size decreased following doping, while the microstrain experienced a significant increase. The low temperature dependent magnetizations for Yb1.85Mn0.15O3 and Eu1.85M0.15O3 nanostructures under a magnetic field of 200 Oe were investigated. Curie–Weiss law was employed to determine the magnetic configuration of the samples. The values of the effective magnetic moments μeff are 4.89 μB and 3.77 μB for Yb1.85Mn0.15O3 and Eu1.85M0.15O3, whereas the calculated values are 4.531 μB and 3.535 μB, respectively. The shielding properties of Re2-xMnxO3 (ReYb or Eu) nanostructures were studied using the Phy-X/PSD simulation program. The linear attenuation coefficients (LAC) and mass attenuation coefficients (MAC) values of the Yb2-xMnxO3 samples are greater than those of the Eu2-xMnxO3 samples. The half value length (HVL) and tenth value length (TVL) values increased as Mn was added to Re1.85Mn0.15O3 nanostructures. Yb1.85Mn0.05O3 and Eu1.85Mn0.05O3 nanostructures have the highest mean free path (MFP) values of 3 cm and 4 cm, respectively, at an energy of 5 MeV. The exposure build-up factor (EBF), and energy absorption build-up factor (EABF) values affected by the host rare earth oxide and the amount of Mn doping. The Re1.85Mn0.15O3 nanostructures exhibit a greater capacity to absorb photons with lower energy rather than higher energy. Yb1.85Mn0.15O3 nanostructure demonstrates exceptional neutron shielding capacities.

Synthesis, crystal structure, and magnetic properties of Ni[formula omitted]CrBO[formula omitted]

Ni2CrBO5 has been synthesized and investigated by X-ray diffraction, dc magnetization, and specific heat measurements. The unusual cation distribution has been established: the M1 and M3 sites are occupied by Ni2+ ions, the M2 site is by Cr3＋ ions, and the M4 site is mixed, featuring both Ni2+ and Cr3＋ ions. The magnetic order onsets at TN= 140 K, which is confirmed by a λ-type peak in specific heat, followed by the dome-shaped anomaly of the magnetization at about 30 K. In the magnetically ordered state, a remarkable sequence of temperature-induced magnetization reversal sensitive to the measurement’s regime is observed. Dominant antiferromagnetic interactions are characterized by the Weiss temperature θ= −73 K. The effective magnetic moment of 5.37 μB per formula unit is close to the spin-only one. The effect of the cation distribution on the magnetic properties is discussed.

Investigation of optical and magnetic properties of 3d-4d transition metal ion based double Perovskite: Sr2MnRuO6

Investigation of physical properties in double perovskites, A2B′B″O6, containing 3d/4d transition metal ions at the B sites is an interesting avenue of research. In this study, we focus on Sr2MnRuO6, exploring its structural, morphological, optical and magnetic properties. Sr2MnRuO6 was synthesized in single phase using solid-state reaction route. It crystallizes in a tetragonal structure (space group I4/mcm, #140) with lattice parameters a = 5.4633 (2) Å, c = 7.9419 (1) Å. X-ray diffraction analysis revealed no super lattice reflections, indicating disorder in the B-site cations.The Jahn-Teller distortion in Mn-O6 octahedra,as revealed by XRD results, indicates a high spin state for the Mn3+ ion. The stoichiometric ratio of Sr: Mn: Ru (∼2:1:1), as determined by bond valence sum calculations and confirmed by energy dispersive x-ray spectroscopy agree well with the nominal composition of Sr2MnRuO6. Diffuse reflectance spectroscopy showed strong absorption throughout the visible region with a direct band gap of ∼3 eV, indicating Sr2MnRuO6 is a potential candidate for optical applications. Huge photoluminescence emission observed in the visible region is attributed to Mn3+ ions. The temperature dependence of molar susceptibility data indicates a paramagnetic to antiferromagnetic transition around 195 K. The possible super exchange paths for antiferromagnetic interaction are Ru5+- 4d3 (t2g3eg0) − O1 − Ru5+- 4d3 (t2g3eg0) along the z axis, or Ru5+- 4d3 (t2g3eg0) − O2 − Ru5+- 4d3 (t2g3eg0) in the xy-plane, with the angles between these orbitals being nearly 180°. At low temperatures under a 10,000 Oe field, spin glass type magnetic behaviour is observed. The effective magnetic moment (6.17 μB) obtained from the Curie-Weiss fit from 260 K to 290 K nearly matched with the theoretical resultant effective moment (6.24 μB) by considering Mn3+ ions in HS state and Ru5+ ions.Specific heat measurements revealed no long-range magnetic ordering down to 2 K, further suggesting the role of cationic disorder in the magnetic behaviour of Sr2MnRuO6.

SYNTHESIS, CHARACTERIZATION, DFT, AND BIOLOGICAL ASSAY OF NEW XANTHATE COMPLEXES WITH NITROGEN BASES

This study introduces a new series of complexes and adducts, denoted by [M(2-PhOEtXant)2.nL], where M represents Mn(II), Fe(II), Co(II), or Ni(II), and the ligand (2-PhOEtXant) is 2-Phenoxyethylxanthate. Varying ligands, including pyridine, piperidine, quinoline, ethylenediamine, and (1,10)-phenanthroline, are explored based on the value of n. Comprehensive characterization, encompassing techniques like 1H-NMR, 13C-NMR, FTIR, AA, CHN analysis, UV-visible spectroscopy, and magnetic property measurements, is employed. Results indicate an octahedral geometry for these complexes, as revealed by effective magnetic moment measurements and electronic spectra analysis. The compounds exhibit noteworthy antioxidant properties, demonstrated through the DPPH radical scavenging method, highlighting their potential as effective antioxidants. Moreover, the complexes display enhanced antibacterial activity against microbial strains compared to free ligands. This research not only delves into the coordination chemistry of these complexes but also underscores their diverse applications. Combining experimental methods with computational insights using Density Functional Theory (DFT) enhances the understanding of dithiolate transition metal complexes. The alignment of computational and experimental outcomes strengthens the reliability of the findings, laying a robust foundation for interdisciplinary exploration. The identified potential applications in optoelectronics, along with the notable antioxidant and antibacterial activities, position these complexes as promising contenders for advanced technologies and scientific applications.

Low-temperature properties of magnetically frustrated rare-earth zirconates A 2Zr2O7

Rare-earth A 2Zr2O7 zirconates have attracted considerable attention of the scientific community for their complex magnetic, electronic and material properties applicable in modern technologies. The light rare-earth members of the series, crystallising in the pyrochlore variant of cubic crystal structure, have been studied in detail. The heavier A 2Zr2O7 compounds have been investigated mainly from the material properties viewpoint, focussing on their thermal properties and stability at high temperature and pressure. Low-temperature studies were mostly missing until recently. We present the low-temperature magnetic and thermodynamic properties of A 2Zr2O7 with A = Y, La, Nd, Eu, Gd, Tb, Dy, Ho, Tm, Yb, and Lu, well covering the whole series, newly synthesised by high-temperature sintering and melting methods. X-ray diffraction reveals and confirms the ordered pyrochlore structure in the light members, the disordered cubic structure of the defect-fluorite type in A 2Zr2O7 with A = Y, Gd–Yb, and finally the lower symmetry rhombohedral structure in the end-member Lu2Zr2O7. The specific heat of the investigated compounds is dominated by a low-temperature anomaly associated with magnetic ordering: long-range in light rare-earth zirconates; and short-range in heavier members. The effective magnetic moment in the studied compounds, determined by fitting the magnetisation data to the Curie–Weiss formula, is in good agreement with the expected value of the A 3+ free ion. The magnetic properties have been revealed to be strongly influenced by the geometric frustration of the magnetic moments of both the pyrochlore structure, as well as the face centred cubic lattice created by the cations of the defect-fluorite structure, but connected also to intrinsic atomic disorder. The experimental results are discussed in the framework of previous studies on A 2Zr2O7 zirconates, as well as other A 2 B 2O7 compounds.

J[formula omitted] Mott-insulating to S = 0 metal transition in Ce@Y-doped Y[formula omitted]NiIrO[formula omitted]

Double perovskite oxides (DPOs) having 3d-5d electrons provide an optimal field to investigate the entanglement between spin–orbit coupling and electron correlation, displaying unusual physical phenomena. Here, we predicted a large magnetic anisotropy energy (MAE) constant of 1.7 × 108 erg/cm3 in a pristine ferrimagnetic (FiM) Y2NiIrO6 DPO with the magnetic easy axis of the monoclinic b-axis. The estimated Curie temperature (TC) of 198 K using the Heisenberg model agrees well with the experimentally observed value of 192 K. Antiferromagnetic coupling between Ni and Ir ions is confirmed, which supports the FiM as a ground state of the system. Furthermore, it is found that the motif displays a Mott-insulating nature because of the exceptional Jeff=12 state of Ir+4 with an effective magnetic moment (meff.) of ∼2.19μB/u.c. (per unit cell), where Ni/Ir ion contains 1.68/−0.49μB. Upon substitution of Ce at Y-site (Ce@Y), few states grow at the Fermi level which belongs to Ir 5d orbitals and meff. enhanced to 3.13 μB/u.c., while FiM survives as a ground state. Along with this, Ni moment remains unchanged, while it substantially reduces to −0.10μB for Ir ion which leads to be in a ＋ 3 (5d6) state with S = 0 and almost persists in the paramagnetic phase. Due to the larger atomic radii of Ce than that of Y, the Ce@Y-doped motif exhibits a large structural distortion as compared to the pristine one, which increases the MAE and TC values simultaneously. Furthermore, calculated enthalpies of formation, distinct elastic constants, and phonon dispersion spectrums ensure the thermodynamic, mechanical, and dynamical stability of the pristine as well as the Ce@Y-doped system, respectively.

Anionic and Magnetic Ordering in Rare Earth Tantalum Oxynitrides with an n = 1 Ruddlesden-Popper Structure.

The new compounds R2TaO4-xNx with R = La, Ce, Nd, and Eu and 1.20 ≤ x ≤ 2.81 have been obtained by a solid-state reaction between metal nitrides and oxides or oxynitrides under N2 gas at temperatures between 1200 and 1700 °C. They are the first examples of rare earth transition metal oxynitrides with an n = 1 Ruddlesden-Popper structure and show different anion stoichiometries, crystal structures, and magnetic properties. Synchrotron X-ray powder diffraction and electron diffraction indicate that the lanthanum, cerium, and neodymium compounds crystallize in the orthorhombic space group Pccn, with cell parameters a = 5.72949(2), b = 5.73055(5), and c = 12.77917(6) Å for La2TaO1.31N2.69, a = 5.70500(5), b = 5.71182(4), and c = 12.61280(7) Å for Ce2TaO1.19N2.81, and a = 5.70466(3), b = 5.70476(5), and c = 12.32365(5) Å for Nd2TaO1.46N2.54. In contrast, Eu2TaO2.80N1.20 shows a tetragonal I41/acd superstructure doubling the c axis, with parameters a = 5.71867(2) and c = 25.00092(19) Å. Refinement of neutron powder diffraction data of Ce2TaO1.19N2.81 indicated the nitrogen order in the two equatorial positions of the tantalum octahedron, with refined N/O occupancies of 0.930(7)/0.070 and 0.876(13)/0.124, and the axial position is occupied by 50% of each anion. This anion ordering agrees with the distribution predicted by Pauling's second crystal rule. Magnetization measurements show that the cerium and europium compounds are ordered magnetically at low temperatures, while the neodymium compound remains paramagnetic down to 2 K, as a consequence of suppression of the effective magnetic moment of the latter when reducing the temperature.

Magnetic-dipole transitions in free lanthanide (3+) ions Ln IV

Oscillator strengths have been evaluated for magnetic-dipole transitions in free lanthanide (3+) ions: Ce IV, Pr IV, Nd IV, Er IV, Tm IV, and Yb IV, within ground-state 4fN configurations. The calculations are based on known experimental 4f-electronic energy levels in these ions. The wave functions used are in LS-coupling scheme or in intermediate coupling approximation (Pr IV, Er IV, Tm IV). The obtained values have been compared with other theoretical and experimental results. It has been found that about 2/3 of the values of the magnetic moments in these optical transitions correspond to the ground-state effective magnetic moments in the free ions Ln IV.

Stability Enhancement by Zero‐Point Spin Fluctuations: A Quantum Perspective on Bloch Point Topological Singularities

AbstractBloch points represent singularities within magnetic materials. From a macroscopic viewpoint, their cores are points where the magnetization vector is undefined, resulting in unique topological characteristics that influence the magnetic behavior of their hosts. The picture is very different at the microscopic level, where quantum effects enter the scene. The spin variables' quantum dynamics effect on the BP's stability is revealed. Zero‐point fluctuations, intrinsic fluctuations within the quantum mechanical ground state originating from the uncertainty principle, play a fundamental role. It is found that quantum fluctuations bloom in the vicinity of the singularity, thereby reducing the effective magnetic moment in its neighborhood. This increases the overall stability of the BP. These methods also allow for a characterization of the magnonic eigenmodes surrounding and bound to the singularity. The latter leads to predict on quite general grounds several features of the magnonic spectra, its degeneration structure, and its splitting response under a magnetic field. The last result is coherent with the association of a magnetic moment to the orbital angular momentum of the magnons. This approach allows integration with multiscale algorithms to provide a realistic description of generic topological singularities.

The magnetic and electric transport properties in erbium-doped layered perovskite iridate Sr2–xErxIrO4

The 5d oxide Sr2IrO4 with a layered perovskite structure has been investigated due to its peculiar Jeff = 1/2 insulating ground state. In this research, we investigate the evolution of magnetic and electric transport properties of Er-doped polycrystalline perovskite iridates Sr2–xErxIrO4 (0 ≤ x ≤ 0.06). Er3+ is magnetic and can thus provide magnetic interactions with Ir. Also, Er3+ doping introduces a carrier-doping effect. We find that substituting Sr2+ with Er3+ still preserves the I41/acd crystal structure, while it causes the rotation of IrO6 octahedra φ to decrease. In this case, the Ir–O1–Ir bond angle increases and the tetragonal distortion c/a decreases. The magnetic properties present a suppressed transition temperature, a decreased Curie–Weiss temperature, and an increased effective magnetic moment. The electrical resistivity of the doped samples decreases with doping, which originates from the crystal distortion and electron doping. Theoretical calculations represent an increase in band filling and an improvement in the conduction property with doping.