Spontaneous Magnetic Moment Research Articles

Weyl fermion excitations in the ideal Weyl semimetal CuTlSe2

An ideal Weyl semimetal is characterized by a dispersion in which only Weyl cones intersect the Fermi level, with low-energy behavior being governed by Weyl fermions. Although ideal Weyl semimetals have long been anticipated, only a few are realized in nonmagnetic materials. In this study, we confirm the presence of Weyl-fermion excitations in the ideal Weyl semimetal CuTlSe2 via a combination of magnetoresistance, Hall-effect, magnetic-susceptibility, nuclear magnetic resonance (NMR), and muon-spin relaxation (µSR) experiments. Magnetoresistance measurements reveal a negative longitudinal magnetoresistance (LMR), which scales as B2, while Hall-effect results indicate a predominant contribution from Weyl fermions with a hole-type charge. Magnetic susceptibility and µSR measurements indicate the lack of any intrinsic spontaneous magnetic moments down to base temperature. Finally, the NMR results can be modeled by a two-component effective Hamiltonian, which reproduces well the temperature-dependent Cu63 NMR (T1T)−1 factor, shown to scale as T2 below 100 K and as T1 above 100 K. Overall, we find that the extremely low concentration (1017cm−3) of carriers in CuTlSe2 originates from an ideal nonmagnetic Weyl semimetallic state, persisting up to a thermal excitation energy of 9 meV (100 K), above which trivial electronic bands close to EF take over. Our findings highlight CuTlSe2 as a new member of the intriguing class of Weyl semimetals. Published by the American Physical Society 2024

Structural transformations of low-nickel Fe-Ni alloys probed by Mössbauer spectroscopy

The structure and magnetic state of Fe100-xNix alloys (x ≤ 20) quenched from 1100 °С have been studied by means of Mössbauer spectroscopy, X-ray diffraction, transmission electron microscopy, and magnetization measurements. The concentration dependences of the lattice parameter of bcc structure and of spontaneous magnetic moment were measured at room temperature. From the analysis of Mössbauer spectra, concentration dependences of average hyperfine parameters have been determined. Both isomer shift and hyperfine field increase with increasing Ni content in the alloy. Fitting of the spectra with a set of subspectra gives grounds to conclude that the structure of quenched Fe-Ni samples represents a system of bcc regions of varying content, which is formed as a result of separation of the alloy composition. This conclusion is supported by the data of transmission electron microscopy.

Magnetism, phase transition, and magnetocaloric effects of Co2Nb0.8Ga1.2 and Co2Nb1.2Ga0.8 Heusler alloys

Magnetism, phase transition, and magnetocaloric effects of Co2Nb0.8Ga1.2 and Co2Nb1.2Ga0.8 alloys were studied. The measured data show that the TC of Co2Nb1.2Ga0.8 and Co2Nb0.8Ga1.2 are 390 K and 250 K, respectively. Interestingly, calculated the high magnetic susceptibility and spontaneous magnetic moment special magnetic behavior was discovered. The spin fluctuation theory was used to prove the character of flowing electron ferromagnet characteristics in this series of alloys find the T0 and TA of the Co2Nb0.8Ga1.2 alloy are 0.268×103 K, and 0.984×103 K, respectively. Meanwhile, from the magnetocaloric effect, it can be found that the isothermal magnetic entropy change ΔSM was 1.8 J/kg⋅K of under a 5 T field while possessing a large refrigeration temperature region. The results show that changing the ratio of the Nb atom to the Ga atom can effectively reduce the Curie temperature and lay the foundation for the subsequent design of room temperature refrigerants.

Nonzero Spontaneous Magnetic Moment along the b-Axis and the 2-Fold Spin Reorientation Transition in a Er0.4Gd0.6FeO3 Single Crystal

Single crystal Er0.4Gd0.6FeO3 (EGFO) was grown by optical floating-zone method. The magnetic properties at three crystallographic axes were investigated in detail. Two special magnetic characteristics were found in EGFO. One is that nonzero spontaneous magnetic moment along crystalline b-axis exists below ∼45 K. This phenomenon is unusual for most of rare-earth orthoferrites. Another one is that the special 2-fold spin reorientation transition was observed. Such a transition can be defined as Γ4 → Γ3 → Γ4, which is the result of the competitions of Er3+–Fe3+ and Gd3+–Fe3+ interactions with Fe3+–Fe3+ interaction at different temperature areas. In addition, the result of spin reorientation transition at different magnetic fields suggested that a magnetic field can modify the anisotropy interaction between rare-earth ions and Fe3+ ions. This work is meaningful for further studying the physical phenomenons in RFeO3 and their potential applications.

Structural ordering, magnetic and electrical transport properties in Ni60-xFe13+xGa27 Heusler alloys

The evolutions of phase transformation, magnetic and electrical transport properties with the change of Fe concentration have been systematically investigated in a series of Ni60-xFe13+xGa27 (x = 0–10) Heusler alloys. The structure and heat flow measurements reveal every sample undergoes a disordered-ordered transition from a disordered B2 structure to a L21 ordered structure, and a first-order structural transformation from the L21 cubic structure to a L10 tetragonal structure is corresponding to the martensitic transformation (MT). With increasing Fe concentration, the disordered-ordered transition and ferromagnetic transition shift to higher temperature, while the MT shifts to lower temperature. According to phase diagram established in the present investigation, it is also found that the increase of Fe content can convert the first-order MT from a paramagnetic type to a ferromagnetic one, which is accompanying by an obvious increase of both effective and spontaneous magnetic moments. Furthermore, the calculated magnetocrystalline anisotropy constant (K1) of the studied alloys monotonically increases as Fe increases. It is evident that the magnetic degrees of freedom in these two MTs remain almost unchanged so that the electron-spin scattering doesn't change, which results in the resistivity difference between the austenitic and martensitic states is feeble. Such an intrinsic nature leads to a weak magnetoresistance (MR) and baroresistance (BR) effects in the studied samples because of only contribution of electron-lattice scattering change on the resistivity. This demonstrates from a negative perspective that the electron-spin scattering change originated from the variation in the magnetic degrees of freedom acts as a dominant role in improvement of the MR and BR effects for the Heusler system possessed the first-order MT.

Localized magnetism, magnetic entropy change and critical properties of Mn[formula omitted]NbS2 single crystals

Magnetic properties, magnetic entropy change and critical behavior of Mn1/4+δNbS2 single crystals have been investigated by easy axial magnetization measurements. The magnetization as a function of temperature (T) under fixed magnetic field H = 1 kOe M (T, 1 kOe) shows two magnetic phase transitions at around 45 K and 105 K, respectively, suggesting the intertwining of Mn1/3NbS2 and Mn1/4NbS2. At paramagnetic state, M (T, 1 kOe) is well captured by the Curie–Weiss law and the effective magnetic moment is deduced to be 5.9 ±0.2μB/Mn, corresponding to a localized Mn2+ ion with S = 52. At T = 2 K, the magnetization saturates quickly around 200 Oe and the spontaneous magnetic moment is estimated to be 5.0(1)μB/Mn. The derived effective and saturation moment indicate that the spin moment of the intercalants are hardly affected by the hosts. In accordance with the two magnetic phase transitions, magnetic entropy change ΔSM shows two series of peaks. At ΔH=7 T, the maxima of ΔSM reach 2.2(8) and 2.6(2) J kg−1 K−1 at 45 K and 105 K, respectively. Analysis of the critical exponents gives β = 0.3593(1), γ = 1.1483(3) and δ = 3.968(3). Although the deduced exponents can fulfill the scaling equations, it is found that they cannot be categorized into a single theoretical model, implying competing magnetic couplings in this crystal.

First-principles study of polar magnets corundum double-oxides Mn2FeMO6 (M = W and Mo)

The physical properties of the corundum double-oxides Mn2FeMO6 (M = W and Mo) are investigated using density functional theory (DFT). The structure relaxation in different spin orders are performed and ferrimagnetic is found the most stable magnetic phase. The compounds are dielectric materials with band gap values 1.84 and 2.03 eV. These materials are polar magnets because of the coexistence of contradictory properties such as polarization and magnetization, which are observed very rarely. The electric polarization arises due structure distortion and cation orbital configuration of M atom, while the magnetization occurs due to unpaired dn of Mn and Fe orbital configuration. The compounds understudy are suitable for ferroelectric and magneto-electric applications due to their large spontaneous polarization (58.16 and 69.24 µC/cm2) and magnetic moments (3 and 3.43 µB/f.u). These multiferroic Mn2FeMO6 exhibit a profound interplay between electrical polarization and the applied magnetic field. The calculated values of piezoelectric coefficient, d33 = 264 and 606 pC/N are comparable to lead-based piezoelectric materials. A set of mechanical parameters revealed that Mn2FeMO6 are mechanically stable in rhombohedral phase. The applied strain has great influence on the physical properties of these two compounds.

Spontaneous orbital magnetization of mesoscopic dipole dimers

Ensembles of gold nanoparticles present a magnetic behavior which is at odds with the weakly diamagnetic response of bulk gold. In particular, an unusual ferromagnetic order has been unveiled by several experiments. Here we investigate if the combined effect of orbital magnetism of conduction electrons and interparticle dipolar interaction can lead to magnetic ordering. Using different model systems of interacting mesoscopic magnetic dipoles, together with a microscopic description of the electron dynamics within the nanoparticles, we find that a spontaneous magnetic moment may arise in dimers of metallic nanoparticles when the latter are characterized by a large orbital paramagnetic susceptibility.

Longitudinal remagnetization of uniaxial antiferromagnetic nanoparticles: the role of spontaneous magnetic moment.

A kinetic theory of magnetic response of uniaxial antiferromagnetic nanoparticles is presented. Within the developed framework, a particular case when an external field is applied strictly along the anisotropy axis is considered in detail. Analysis of the relaxation spectrum of an antiferromagnetic particle with a spontaneous magnetic moment is performed. It is shown that in a wide frequency range the magnetic response of such particle is determined entirely by the relaxation mode with the longest time. An analytical expression for this time that explicitly contains a value of the decompensation magnetic moment is derived. Also, simple formulae for both static and dynamic longitudinal magnetic susceptibility of an antiferromagnetic nanoparticle are obtained. According to them, longitudinal susceptibility grows quadratically with the value of the spontaneous magnetic moment. Besides, if the latter is not zero, the change of the static susceptibility with temperature turns out to be non-monotonic. The influence of the spontaneous magnetic moment of the particle on the magnetization curves in strong fields is analysed using both energy approach and kinetic theory. The calculated dependences of the dynamic coercivity on the amplitude and variation rate of the applied field are qualitatively compared with experimental data. This article is part of the theme issue 'Transport phenomena in complex systems (part 2)'.

Magnetically Separable Fe3O4/SiO2/TiO2 Photocatalyst Composites Prepared through Hetero Agglomeration for the Photocatalytic Degradation of Paraquat

A photocatalyst supported on magnetic material allows the simple technique by using an external magnetic material to separate photocatalyst from the treated water. Thus, it is a magnetically separable nanoparticles photocatalyst (MSNP). The use of superparamagnetic nanoparticles that do not pose spontaneous magnetic moment thus could be dispersed in water and can be recollected easily by an external magnetic bar. We prepare Fe3O4/SiO2/TiO2 composite by hetero agglomeration of Fe3O4/SiO2 and TiO2 at a pH range of 3 to 6.2 in an aqueous slurry.The Fe3O4/SiO2 was prepared via co-precipitation of iron (II) and iron (III) ionic solution containing ammonium hydroxide and sodium silicate. The prepared composites were characterized by XRD, TEM, FTIR, and VSM, while the photocatalytic activities were tested toward paraquat in water. Based on zeta potential values, the Fe3O4/SiO2and TiO2 were being hetero agglomerated at pH 5 to obtain Fe3O4/SiO­2/TiO2 composite. The XRD characterization confirmed the presence of anatase, rutile, and magnetite crystal phases. TEM images showed that the Fe3O4 was covered by SiO2 and randomly attached to TiO2. The observed FTIR peak at 940-960 cm-1 attributed to -Si-O-Ti- bonding mode, ensuring photocatalyst (TiO2) adherence to the Fe3O4/SiO2 cluster. The prepared Fe3O4/SiO2/TiO2 composite showed good photocatalytic activity for the paraquat removal and showed a good magnetic property (VSM measurement)

Magnetic and Critical Properties of Cr1/3NbS1.86 with TC = 56 K

The magnetic and critical properties of a TeBr‐transported CrNbS single crystal using magnetic susceptibility χ(T) and isothermal magnetization M(H) measurements are studied. A paramagnetic‐to‐ferromagnetic phase transition temperature (T C) is determined to be 56 K from χ(T) and an Arrott–Noakes’ plot. At high temperatures (T ≥ 85 K), χ(T) is well captured by the Curie–Weiss law and the effective magnetic moment is derived as P eff = 3.77 μ B per Cr. The signature of helical and chiral soliton spin structures is absent, as inferred from the (H, 2 K) data. The spontaneous magnetic moment P = 1.66 μ B per Cr compared with P eff, leading to the Rhodes–Wohlfarth ratio to be 1.75, is rather small, suggesting a slightly itinerant magnetism. However, the spin‐wave (SW) model describes the temperature‐dependent magnetization better than the single‐particle (SP) model. Further, analysis of the critical exponent yields β = 0.3852(1) and γ = 1.3575(4), which are close to the theoretical prediction of the 3D Heisenberg model and therefore suggests dominant short‐range ferromagnetic interactions. Finally, the deviation of the critical exponents from the theoretical model and the violation of Widom scaling law is discussed.

Directed synthesis of a hybrid improper magnetoelectric multiferroic material

Preparing materials which simultaneously exhibit spontaneous magnetic and electrical polarisations is challenging as the electronic features which are typically used to stabilise each of these two polarisations in materials are contradictory. Here we show that by performing low-temperature cation-exchange reactions on a hybrid improper ferroelectric material, Li2SrTa2O7, which adopts a polar structure due to a cooperative tilting of its constituent TaO6 octahedra rather than an electronically driven atom displacement, a paramagnetic polar phase, MnSrTa2O7, can be prepared. On cooling below 43 K the Mn2+ centres in MnSrTa2O7 adopt a canted antiferromagnetic state, with a small spontaneous magnetic moment. On further cooling to 38 K there is a further transition in which the size of the ferromagnetic moment increases coincident with a decrease in magnitude of the polar distortion, consistent with a coupling between the two polarisations.

Role of anisotropic Coulomb interactions in the superexchange coupling of mixed-valent Mn3O4

We report the importance of anisotropic Coulomb interactions in $\mathrm{DFT}+U$ calculations of the electronic and magnetic properties of ${\mathrm{Mn}}_{3}{\mathrm{O}}_{4}$. The effects of anisotropic interactions in ${\mathrm{Mn}}^{2+}$ and ${\mathrm{Mn}}^{3+}$ are examined separately by defining two different sets of Hubbard parameters: ${U}^{2+}$ and ${J}^{2+}$ for ${\mathrm{Mn}}^{2+}$ and ${U}^{3+}$ and ${J}^{3+}$ for ${\mathrm{Mn}}^{3+}$. The anisotropic interaction in ${\mathrm{Mn}}^{3+}$ has significant effects on the physical properties of ${\mathrm{Mn}}_{3}{\mathrm{O}}_{4}$ including local magnetic moments, canted angle, spontaneous magnetic moment, and superexchange coupling, but that in ${\mathrm{Mn}}^{2+}$ has no noticeable effect. Weak ferromagnetic interchain superexchange observed experimentally is predicted only if a sizable anisotropic interaction is considered in ${\mathrm{Mn}}^{3+}$. By analyzing the eigenoccupations of the on-site Mn density matrix, we find that the spin channel involving ${\mathrm{Mn}}^{3+}\phantom{\rule{4pt}{0ex}}{d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ orbitals, which governs the ${90}^{\ensuremath{\circ}}$ correlation superexchange, is directly controlled by the anisotropic interactions. These findings indicate that the exchange correction $J$ for the intraorbital Coulomb potential is critical for the first-principles description of Mn oxides containing ${\mathrm{Mn}}^{3+}$ or ${\mathrm{Mn}}^{4+}$.

Crystal structure and magnetic properties of Al2NdNi3 studied by experimental and first-principles

The Al2NdNi3 single-phase alloy was prepared by melting stoichiometric Al, Nd, and Ni in the nonconsumable arc furnace filled with argon and then homogenizing annealing at a high temperature. The crystal structure of Al2NdNi3 was analyzed by an X-ray powder diffraction technique, Rietveld refinement analysis, and the first-principles simulation calculation method. The results show that Al2NdNi3 crystallizes in ordered variant of CaCu5-type structure (space group P6/mmm, No. 191, hP6), and the lattice parameters of a ​= ​5.1247 (1) Å, c ​= ​4.0941 (1) Å, Z ​= ​1 and Dcalc ​= ​6.68 ​g/cm3. The temperature-dependent susceptibility data shows field sensitive behaviour of Al2NdNi3 with low temperature transformation of magnetic ordering below ~100 ​K Al2NdNi3 exhibits ferromagnetic properties at low temperatures and has a Curie temperature (Tc) of 253 ​K in field of 50 ​Oe with the saturation magnetic moment (Ms) of 0.25 μB/f.u. in field of 8 ​T and coercivity (Hc) of 0.16 ​T at 2 ​K. The simulation results also show that Al2NdNi3 is a ferromagnet with a spontaneous magnetic moment of 0.28 μB/f.u., and it is believed that the spontaneous magnetization of this alloy originate from the electron spin in the Nd(1a)-4f band.

Epitaxy, exfoliation, and strain-induced magnetism in rippled Heusler membranes

Single-crystalline membranes of functional materials enable the tuning of properties via extreme strain states; however, conventional routes for producing membranes require the use of sacrificial layers and chemical etchants, which can both damage the membrane and limit the ability to make them ultrathin. Here we demonstrate the epitaxial growth of the cubic Heusler compound GdPtSb on graphene-terminated Al2O3 substrates. Despite the presence of the graphene interlayer, the Heusler films have epitaxial registry to the underlying sapphire, as revealed by x-ray diffraction, reflection high energy electron diffraction, and transmission electron microscopy. The weak Van der Waals interactions of graphene enable mechanical exfoliation to yield free-standing GdPtSb membranes, which form ripples when transferred to a flexible polymer handle. Whereas unstrained GdPtSb is antiferromagnetic, measurements on rippled membranes show a spontaneous magnetic moment at room temperature, with a saturation magnetization of 5.2 bohr magneton per Gd. First-principles calculations show that the coupling to homogeneous strain is too small to induce ferromagnetism, suggesting a dominant role for strain gradients. Our membranes provide a novel platform for tuning the magnetic properties of intermetallic compounds via strain (piezomagnetism and magnetostriction) and strain gradients (flexomagnetism).

Observation of strong excitonic magneto-chiral anisotropy in twisted bilayer van der Waals crystals

The interplay between chirality and magnetism generates a distinct physical process, the magneto-chiral effect, which enables one to develop functionalities that cannot be achieved solely by any of the two. Such a process is universal with the breaking of parity-inversion and time-reversal symmetry simultaneously. However, the magneto-chiral effect observed so far is weak when the matter responds to photons, electrons, or phonons. Here we report the first observation of strong magneto-chiral response to excitons in a twisted bilayer tungsten disulfide with the amplitude of excitonic magneto-chiral (ExMCh) anisotropy reaches a value of ~4%. We further found the ExMCh anisotropy features with a spectral splitting of ~7 nm, precisely the full-width at half maximum of the excitonic chirality spectrum. Without an externally applied strong magnetic field, the observed ExMCh effect with a spontaneous magnetic moment from the ferromagnetic substrate of thulium iron garnet at room temperature is favorable for device applications. The unique ExMCh processes provide a new pathway to actively control magneto-chiral applications in photochemical reactions, asymmetric synthesis, and drug delivery.

Experimental observation and theoretical analysis of spontaneous magnetic moment of Rb atom clusters

For the magnetism of alkali metal clusters, it is difficult to determine the number of atoms and the magnetic moment of isolated atoms cluster. In this paper, we investigate the magnetic moment of single atomic molecule <sup>87</sup>Rb<sub>1</sub> and 14 kinds of cluster particles (<sup>87</sup>Rb)<inline-formula><tex-math id="Z-20210617162030">\begin{document}${}_{n'} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20210031_Z-20210617162030.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20210031_Z-20210617162030.png"/></alternatives></inline-formula> (<inline-formula><tex-math id="Z-20210617161856">\begin{document}$n' $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20210031_Z-20210617161856.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20210031_Z-20210617161856.png"/></alternatives></inline-formula>= 2, 3, 4, ···, 15) in a saturated rubidium vapor sample at about 328 K, by using optical magnetic resonance spectroscopy. The experimental results show that there is a relationship <i>f</i><inline-formula><tex-math id="Z-20210617161925">\begin{document}${}_{n'} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20210031_Z-20210617161925.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20210031_Z-20210617161925.png"/></alternatives></inline-formula> = <i>f</i> */<inline-formula><tex-math id="Z-20210617161921">\begin{document}$n' $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20210031_Z-20210617161921.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20210031_Z-20210617161921.png"/></alternatives></inline-formula> between the resonant frequencies <i>f</i><inline-formula><tex-math id="Z-20210617161939">\begin{document}${}_{n'} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20210031_Z-20210617161939.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20210031_Z-20210617161939.png"/></alternatives></inline-formula> of 14 kinds of cluster particles (<sup>87</sup>Rb)<inline-formula><tex-math id="Z-20210617161944">\begin{document}${}_{n'} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20210031_Z-20210617161944.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20210031_Z-20210617161944.png"/></alternatives></inline-formula> and the resonant frequencies <i>f</i> * of <sup>87</sup>Rb<sub>1</sub>. The magnetic moment and their resonance amplitudes show two different relationships with the <inline-formula><tex-math id="Z-20210617162058">\begin{document}${n'} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20210031_Z-20210617162058.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20210031_Z-20210617162058.png"/></alternatives></inline-formula> odevity. When the particles have an odd number of 5s electrons, they must have spontaneous magnetic moment, and the value of magnetic moment increases with <i>n</i> and decreases inverse proportionally with the combined angular momentum <i>F</i> of the cluster particles. The amplitude obtained from resonance spectrum complies with the variation law of magnetic moment value. On the other hand, for the cluster particles with <i>n</i> being even number, the magnetic moment value becomes 0 and the amplitude is also 0 in the most cases, except for the cluster particles <sup>87</sup>Rb<sub>2</sub> with <i>n</i> = 2 i.e. two 5s electrons, which is caused by the Jahn-Teller effect of the linear molecules, and the magnetic moment value is consistent with the calculation results of the odd number particles. When <i>n</i> > 2, the coupling effect between the magnetic moments of the Rb cluster shows a long-range ordered antiferromagnetic property with the increase of the number of 5s valence electrons <i>n</i>. The electron configuration and molecular state of the ground state and the lowest excited state of 14 kinds of 2—15 atoms cluster particles <sup>87</sup>Rb<i><sub>n</sub></i>, as well as the stability of each molecular state and the possibility of visible Zeeman effect are obtained by using the molecular orbital-state theory analysis and constructing the <sup>87</sup>Rb<sub><i>n</i>–1</sub> + <sup>87</sup>Rb<i><sub>n</sub></i> atomic cluster model. Furthermore, based on the magnetic moment of diatomic molecules ruler, it is found that when <i>n</i> = <inline-formula><tex-math id="Z-20210617162122">\begin{document}${n'} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20210031_Z-20210617162122.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20210031_Z-20210617162122.png"/></alternatives></inline-formula>, the magnetic moment of (<sup>87</sup>Rb)<inline-formula><tex-math id="Z-20210617161959">\begin{document}${}_{n'} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20210031_Z-20210617161959.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20210031_Z-20210617161959.png"/></alternatives></inline-formula> and <sup>87</sup>Rb<i><sub>n</sub></i> are in strict consistency (the average relative error is only 0.6765%), confirming the corresponding relationship between (<sup>87</sup>Rb)<inline-formula><tex-math id="Z-20210617161951">\begin{document}${}_{n'} $\end{document}</tex-math><alternatives><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20210031_Z-20210617161951.jpg"/><graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="12-20210031_Z-20210617161951.png"/></alternatives></inline-formula> and <sup>87</sup>Rb<i><sub>n</sub></i>. This research will be of great value in the magnetic research of cluster particles.

Epitaxial thin-film Pd1−xFex alloy: a tunable ferromagnet for superconducting spintronics

In the paper we present the results of extensive studies of palladium-rich Pd1-xFex alloy films epitaxially grown on MgO single-crystal substrate. In a composition range of x = 0.01-0.07 these materials are soft ferromagnets, the saturation magnetization and magnetic anisotropy of which can be tuned by its composition. Vibrating sample magnetometry was used to study temperature dependences of spontaneous magnetic moment and to establish the temperature of magnetic ordering (Curie temperature). Ferromagnetic resonance (FMR) measurements at low temperatures in the in-plane and out-of-plane geometries revealed the four-fold in-plane magnetic anisotropy with the easy directions along the <110> axes of the substrate. The modelling of the angular dependence of the field for resonance allowed to extract the cubic and tetragonal contributions to the magnetic anisotropy of the films and establish their dependence on the concentration of iron in the alloy. Experimental data are discussed in the framework of existing theories of dilute magnetic alloys. Using the anisotropy constants established from FMR, the magnetic hysteresis loops are reproduced utilizing the Stoner-Wohlfarth model thus indicating the predominant coherent magnetic moment rotation at low temperatures. The obtained results compile a database of magnetic properties of a palladium-iron alloy considered as a material for superconducting spintronics.

Synthesis of Vanadium Ferrite Nanoparticles By Microwave Assisted Technique

Among the magnetic materials ferrites are of great interest due to its distinctive properties. Ferrites exhibit a spontaneous magnetic moment below a Curie temperature and act as insulators at low temperature. Sincethey have been used in number of technological applications like microwave devices, magnetic and magneto optic recording, data storage etc. The incredible magnetic, electric and dielectric properties of ferrites make them more attractive and applicable in the current field of science and technology. In the present study vanadium ferrite nanoparticles were synthesized by microwave assisted method. The structural properties of synthesized nanoparticles are carried out from X-ray diffraction technique. The presence of peaks confirms the crystalline nature of the vanadium ferrite nanoparticles. The crystal structure, crystalline size (D), Dislocation density (8) is determined from XRD data. Also using Williamson-Hall plot micro strain value is calculated.The different molecular vibrations are confirmed through Fourier Transformed Infrared Spectroscopy (FTIR) vibration spectra. From the Ultra Violet Spectroscopicdata using the Tauc relation, the energy gap (Eg) at the edge of absorbance band is calculated as 4.28eV for direct and 4.84 eV for indirect transition. The morphological studies are done through Scanning Electron Microscope (SEM). From the SEM micrographs we confirm the presence of spherical nanoparticles and they are arranged uniformly. From VSM analysis, we calculated the saturation magnetization as 20.00 emu, coercivity as 125.96 g, and retentivity is 130.45 emu.

Weak ferromagnetism and magnetoelectric coupling through the spin–lattice coupling in (1−x)Pb(Fe2/3W1/3)O3–(x)BiFeO3 (x = 0.1 and 0.4) solid solution

We report on the structure, spin–lattice and magneto-electric coupling in (1−x)Pb(Fe2/3W1/3)O3–(x)BiFeO3(where x = 0.1 and 0.4) (PBFW) solid solution synthesized through two-step solid-state reaction method. The room temperature (RT) crystallographic studies were carried out using x-ray diffraction and neutron diffraction measurements which show a single-phase Pseudocubic crystal system with Pm-3m space group. Rietveld refinement was carried out to obtain the structural parameters using Fullprof software and the observed structural parameters are in good agreement with the previous reports. Temperature-dependent neutron diffraction measurements reveal the presence of commensurate G-type antiferromagnetic structure. The magnetic structure was analyzed using the propagation wave vector k ∼ (½ ½ ½) for both the solid solutions. The obtained lattice constants increase linearly and the magnetic moment decrease with temperature, which shows a remarkable anomaly around the magnetic (TN ∼ 405 K for x = 0.1 and 531 K for x = 0.4) transition temperatures. This anomaly clearly indicates the existence of spin–lattice and magnetoelectric coupling. The magnetic susceptibility (ZFC and FC at 500 Oe) and M–H hysteresis loop measurements show spontaneous magnetic moment due to the Fe3+–O2−–Fe3+ superexchange interaction coexisting with the weak ferromagnetism. Bifurcation of ZFC and FC curve reveals the strong anisotropic nature. Astonishingly, magnetic measurements show the non-zero magnetic moment above TN and broadening of the magnetic transition indicates the presence of short-range uncompensated sublattice weak ferromagnetic clusters in the paramagnetic region. The Mossbauer spectroscopy and electron paramagnetic resonance studies exhibit the RT magnetically ordered system and confirm the +3 state of Fe along with the fraction of Fe2+ ions.