Reduction Of Magnetic Moment Research Articles

Magnetism and electronic structures for B-doped bulk and surface AlN: Ab initio calculations

The magnetism and electronic structures for B-doped bulk and surface AlN are investigated. Our calculations show that the 6.25% B-doped AlN is a half-metallic ferromagnet with a 0.851 eV half-metallic gap. Under an Al-rich condition, the formation energy is 3.83 eV, indicating that the B-doped AlN could be realized experimentally. Electronic structures show that a double-exchange mechanism plays an important role in forming the ferromagnetism. Nitrogen vacancy, emerging in B-doped AlN, would result in a total magnetic moment reduction and half-metallic ferromagnetism loss. For the B-doped surface , calculations show that boron dopants favor the surface layer, and ferromagnetic exchange coupling still exists among the boron dopants.

Effect of annealing on the magnetic properties of ball milled NiO powders

We report systematic investigations on structural and magnetic properties of nanosized NiO powders prepared by the ball milling process followed by systematic annealing at different temperatures. Both as-milled and annealed NiO powders exhibit face centered cubic structure, but average crystallite size decreases (increases) with increasing milling time (annealing temperature). Pure NiO exhibits antiferromagnetic nature, which transforms into ferromagnetic one with moderate moment at room temperature with decreasing crystallite size. The on-set of ferromagnetic behavior in the as-milled powders was observed at higher temperatures (>750K) as compared to bulk Ni (~630K). On the other hand, annealing of as-milled powders showed a large reduction in magnetic moment and the rate of decrease of moment strongly depends on the milling conditions. The observed properties are discussed on the basis of crystallite size variation, defect density, oxidation/reduction of Ni and interaction between uncompensated surfaces and particle core with lattice expansion.

Magnetic properties of small ruthenium clusters in fullerene cage — A DFT study

Encapsulation of small clusters in fullerene cages provides a stable environment for their application in nanoscale functional devices. In this paper, first principles study of Ruthenium as an endohedral dopant in buckminsterfullerene has been carried out using density functional theory. Ruthenium atom has three stable dopant sites inside C 60, with three possible values of magnetic moment (4, 2 and 0 μB). The doping position of Ru atom can be seen to have an effect on HOMO–LUMO gap, formation energy, binding energy and magnetic moment of the fullerene cage. The interaction between Ru and C atoms in different conformations can be explained in terms of Mulliken analysis and density of states analysis. It is also possible to encapsulate more than one Ru atoms in the C 60 cage ( Ru n@ C 60, n = 2–6); encapsulation up to six atoms has been analyzed, after which the process is energetically unfavorable. The geometry of the lowest energy structures, compared to the isolated Ru n clusters, is found to change as a result of encapsulation (e.g., in Ru 3@ C 60 and Ru 5@ C 60). A reduction in magnetic moment of Ru clusters inside fullerene cage as compared to isolated clusters also occurs due to hybridization and confinement effects. The varied magnetic moments of Ru -encapsulated C 60 molecules reveal its applications in molecular magnetic devices and quantum peapods.

Spin-orbit density wave: a new phase of matter applicable to the hidden order state of URu2Si2

We provide a brief review and detailed analysis of the spin-orbit density wave (SODW) proposed as a possible explanation to the ‘hidden order’ phase of URuSi. Due to the interplay between inter-orbital Coulomb interaction and spin-orbit coupling (SOC) in this compound, the SODW is shown to arise from Fermi surface nesting instability between two spin-orbit split bands. An effective low-energy Hamiltonian including single-particle SOC and two-particle SODW is derived, while the numerical results are calculated using density-functional theory (DFT)-based band-structure input. Computed gapped quasiparticle spectrum, entropy loss and spin-excitation spectrum are in detailed agreement with experiments. Interestingly, despite the fact that SODW governs dynamical spin-excitations, the static magnetic moment is calculated to be zero, owing to the time-reversal invariance imposed by SOC. As a consequence, SODW can be destroyed by finite magnetic field even at zero temperature. Our estimation of the location of the quantum critical point is close to the experimental value of 35 T. Finally, we extend the idea of SODW to other SOC systems including iridium oxides (iridates) and two-dimensional electronic systems such as BiAg surface and LaAlO/SrTiO interface. We show hint of quasiparticle gapping, reduction of pre-existing magnetic moment, large magneto-resistance, etc. which can be explained consistently within the SODW theory.

Crystal structure, physical properties, and electronic and magnetic structure of the spin S = 5/2 zigzag chain compound Bi2Fe(SeO3)2OCl3.

We report the synthesis and characterization of the new bismuth iron selenite oxochloride Bi2Fe(SeO3)2OCl3. The main feature of its crystal structure is the presence of a reasonably isolated set of spin S = 5/2 zigzag chains of corner-sharing FeO6 octahedra decorated with BiO4Cl3, BiO3Cl3, and SeO3 groups. When the temperature is lowered, the magnetization passes through a broad maximum at Tmax ≈ 130 K, which indicates the formation of a magnetic short-range correlation regime. The same behavior is demonstrated by the integral electron spin resonance intensity. The absorption is characterized by the isotropic effective factor g ≈ 2 typical for high-spin Fe(3+) ions. The broadening of ESR absorption lines at low temperatures with the critical exponent β = 7/4 is consistent with the divergence of the temperature-dependent correlation length expected for the quasi-one-dimensional antiferromagnetic spin chain upon approaching the long-range ordering transition from above. At TN = 13 K, Bi2Fe(SeO3)2OCl3 exhibits a transition into an antiferromagnetically ordered state, evidenced in the magnetization, specific heat, and Mössbauer spectra. At T < TN, the (57)Fe Mössbauer spectra reveal a low saturated value of the hyperfine field Hhf ≈ 44 T, which indicates a quantum spin reduction of spin-only magnetic moment ΔS/S ≈ 20%. The determination of exchange interaction parameters using first-principles calculations validates the quasi-one-dimensional nature of magnetism in this compound.

Preattentive dysfunction in patients with bipolar disorder as revealed by the pitch-mismatch negativity: a magnetoencephalography (MEG) study.

Mismatch negativity (MMN) and its magnetic counterpart (MMNm) are thought to reflect an automatic process that detects a difference between an incoming stimulus and the sensory memory trace of preceding stimuli. In patients with schizophrenia, an attenuation of the MMN/MMNm amplitude has been repeatedly reported. Heschl's gyrus (HG) is one of the major generators of MMN and the functional alteration of HG has been reported in patients with bipolar disorder. The present study investigated the pitch-MMNm in patients with bipolar disorder using whole-head 306-ch magnetoencephalography (MEG). Twenty-two patients and 22 healthy controls participated in this study. Subjects were presented with two types of auditory stimulus sequences. One consisted of 1,000 Hz standards (probability = 90%) and 1,200 Hz deviants (probability = 10%), and the other consisted of 1,000 Hz standards (90%) and 1,200 Hz deviants (10%). These two tasks were each performed twice. Event-related brain responses to standard tones were subtracted from responses to deviant tones. Patients with bipolar disorder showed a significant bilateral reduction in magnetic global field power (mGFP) amplitudes (p = 0.02) and dipole moments of the MMNm (p = 0.04) compared with healthy controls. Patients with admission experience showed significantly reduced mGFP amplitudes of MMNm compared with patients without admission experience (p = 0.004). Additionally, patients with more severe manic symptoms had smaller mGFP amplitudes of MMNm (ρ = -0.50, p = 0.05). The results of this study suggest that patients with bipolar disorder may exhibit preattentive auditory dysfunction indexed by reduced pitch-MMNm responses. Pitch-MMNm could be a potential trait marker reflecting the global severity of bipolar disorder.

Room temperature ferromagnetism in finite sized ZnO nanoparticles

We report systematic investigations on the evolution of nanostructured ZnO, room temperature ferromagnetism, and tunable optical properties of ZnO nanoparticles prepared by a mechanical alloying process. It was observed that both un-milled and as-milled powders exhibited a wurtzite structure, but average crystallite size decreased and the effective strain increased for the initial periods of milling. Paramagnetic nature observed in un-milled ZnO gradually unveils room temperature ferromagnetic ordering with modest moment and coercivity. A maximum moment of 0.013µB/f.u. at 12kOe applied field and a coercivity of 172Oe were obtained for 40h milled ZnO powder. Thermo-magnetization data reveal a clear magnetic phase transition from ferromagnetic to paramagnetic state around 500°C, which shifts slightly towards higher temperature with an increasing milling period up to 20h. Annealing of as-milled ZnO powder and UV–vis studies display a drastic reduction in room temperature magnetic moment and blue-shifting of excitonic absorption peak. The observed ferromagnetic properties are intrinsic and discussed on the basis of finite size effect, defect density due to oxygen vacancy. These nanoparticles with tunable magnetic and optical properties are promising to find applications in multifunctional spintronic and photonic devices.

Finite Size Effects in Magnetic and Optical Properties of Antiferromagnetic NiO Nanoparticles

We report systematic investigations on structural, magnetic and optical properties of NiO nanoparticles prepared by mechanical alloying. As-milled powders exhibit face centred cubic structure, but average particle size decreases and effective strain increases for the initial periods of milling. Lattice volume increases monotonically with a reduction in particle size. Antiferromagnetic NiO particles exhibit significant room temperature (RT) ferromagnetism with modest moment and coercivity. A maximum moment of 0.0147 μB/f.u at 12 kOe applied field and a coercivity of 160 Oe were obtained for 30 h milled NiO powder. Exchange bias decreases linearly with a decrease in NiO particle size. Thermo-magnetization data reveal the presence of mixed magnetic phases in milled powders and shifts magnetic phase transition towards high temperature with increasing milling. Annealing of milled NiO powder and photoluminescence studies show a large reduction in RT magnetic moment and blue-shifting of band edge emission peak. The observed properties are discussed on the basis of finite size effect, defect density, oxidation/reduction of Ni, increase in number of sublattices, uncompensated spins from surface to particle core, and interaction between uncompensated surfaces and particle core with lattice expansion.

Structural, electrical, magnetic and dielectric properties of rare-earth substituted cobalt ferrites nanoparticles synthesized by the co-precipitation method

Pure nanoparticles of the rare-earth substituted cobalt ferrites CoRExFe2−xO4 (where RE=Nd, Sm and Gd and x=0.1 and 0.2) were prepared by the chemical co-precipitation method. X-ray diffraction, Transmission electron microscopy (TEM), d.c. electrical conductivity, Magnetic hysteresis and Thermal analysis are utilized in order to study the effect of variation in the rare-earth substitution and its impact on particle size, magnetic properties like MS, HC and Curie temperature. The phase identification of the materials by X-ray diffraction reveals the single-phase nature of the materials. The lattice parameter increased with rare-earth content for x≤0.2. The Transmission electron micrographs of Nd-, Sm- and Gd-substituted CoFe2O4 exhibit the particle size 36.1 to 67.8nm ranges. The data of temperature variation of the direct current electrical conductivity showed definite breaks, which corresponds to ferrimagnetic to paramagnetic transitions. The thermoelectric power for all compound are positive over the whole range of temperature. The dielectric constant decreases with frequency and rare-earth content for the prepared samples. The magnetic properties of rare-earth substituted cobalt ferrites showed a definite hysteresis loop at room temperature. The reduction of coercive force, saturation magnetization, ratio MR/MS and magnetic moments may be due to dilution of the magnetic interaction.

Magnetic properties of nanocrystalline ɛ-Fe3N and Co4N phases synthesized by newer precursor route

Nanocrystalline ɛ-Fe3N and Co4N nitride phases are synthesized first time by using tris(1,2-diaminoethane)iron(II) chloride and tris(1,2-diaminoethane)cobalt(III) chloride precursors, respectively. To prepare ɛ-Fe3N and Co4N nitride phases, the synthesized precursors were mixed with urea in 1:12 ratio and heat treated at various temperatures in the range of 450–900°C under the ultrapure nitrogen gas atmosphere. The precursors are confirmed by FT-IR study. The ɛ-Fe3N phase crystallizes in hexagonal structure with unit cell parameters, a=4.76Å and c=4.41Å. The Co4N phase crystallizes in face centred cubic (fcc) structure with unit cell parameters, a=3.55Å. The estimated crystallite size for ɛ-Fe3N and Co4N phases are 29nm and 22nm, respectively. The scanning electron microscopy (SEM) studies confirm the nanocrystalline nature of the materials. The values of saturation magnetization for ɛ-Fe3N and Co4N phases are found to be 28.1emu/g and 123.6emu/g, respectively. The reduction of magnetic moments in ultrafine materials compared to bulk materials have been explained by spin pairing effect, lattice expansion, superparamagnetic behaviour and canted spin structures at the surface of the particles.

Electronic and magnetic properties of Fe clusters inside finite zigzag single-wall carbon nanotubes

Density functional calculations of the electronic structure of the Fe${}_{12}$ cluster encapsulated inside finite single-wall zigzag carbon nanotubes of indices $(11,0)$ and $(10,0)$ have been performed. Several Fe${}_{12}$ isomers have been considered, including elongated shape isomers aimed to fit well inside the nanotubes, and the icosahedral minimum energy structure. We analyze the structural and magnetic properties of the combined systems, and how those properties change compared to the isolated systems. A strong ferromagnetic coupling between the Fe atoms occurs both for the free and the encapsulated Fe${}_{12}$ clusters, but there is a small reduction (3\char21{}$7.4\phantom{\rule{0.16em}{0ex}}{\ensuremath{\mu}}_{B}$) of the spin magnetic moment of the encapsulated clusters with respect to that of the free ones ($\ensuremath{\mu}=38\phantom{\rule{0.16em}{0ex}}{\ensuremath{\mu}}_{B}$). The reduction of the magnetic moment is mostly due to the internal redistribution of the spin charges in the iron cluster. In contrast, the spin magnetic moment of the carbon nanotubes, which is zero for the empty tubes, becomes nonzero (1\char21{}$3\phantom{\rule{0.16em}{0ex}}{\ensuremath{\mu}}_{B}$) because of the interaction with the encapsulated cluster. We have also studied the encapsulation of atomic Fe and the growth of small Fe${}_{n}$ clusters ($n=2$, 4, 8) encapsulated in a short $(10,0)$ tube. The results suggest that the growth of nanowires formed by distorted tetrahedral Fe${}_{4}$ units will be favorable in $(10,0)$ nanotubes and nanotubes of similar diameter.

First principles investigation of Na doping effects on the structural, magnetic, and electronic properties in SrRuO3

The structural, electronic and magnetic properties of Sr1−xNaxRuO3 have been investigated using the pseudo-potential plane wave method within the generalized gradient approximation GGA+U method by first principles. The results show that all structures of Sr1–xNaxRuO3 (x=0, 0.125, 0.25) are ferromagnetic phase. There is a more strong Jahn–Teller distortion of the RuO6 octahedra in Na doped compounds. Na doping cannot induce magnetic phase transition in SrRuO3. A Stoner mechanism for ferromagnetism in SrRuO3 is weakened by Na doping, which can lead to a reduction of effective magnetic moment. Na doping lowers the density of states at Fermi lever and decreases the number of electrons above the Fermi energy, which indicates that the pure SrRuO3 is more metallic than Sr0.875Na0.125RuO3 and Sr0.75Na0.25RuO3. However, the metal-insulator transition has not happened when Na only substitutes on the Sr site in SrRuO3.

First-Principles Study on the Structural and Magnetic Properties of Iron Hydride

The magnetic and structural properties of iron hydride FeH with the double hexagonal close-packed (dhcp) and hexagonal close-packed (hcp) structures are investigated by first-principles density-functional theory calculations with a spin-polarized form of generalized gradient approximation. All the calculations are performed using all-electron full-potential linearized augmented plane wave method. Both dhcp and hcp FeH are ferromagnetic at ambient pressure. The ferromagnetic ordering of the dhcp structure collapses at a pressure of 48 GPa, while that of the hcp structure vanishes gradually from 48 GPa. The modification in the density of states (DOS) due to the applied pressure causes the collapse of the magnetization. The difference in magnetic moment reduction between dhcp and hcp FeH is attributed to their DOS around the Fermi level. The calculated magnetocrystalline anisotropy energies between in-plane and out-of-plane spin orientations are found to be 124 µeV/Fe for the dhcp structure, and 100 µeV/Fe for the hcp structure. The easy axis is in-plane direction for both structures.

Cyclopentadienyl–benzene based sandwich molecular wires showing efficient spin filtering, negative differential resistance, and pressure induced electronic transitions

Using density functional theory, we investigate TM–cyclopentadienyl–benzene sandwich molecular wires (SMWs) which are composites of TM–cyclopentadienyl and TM–benzene wires (TM = transition metal (V, Fe)). All the SMWs are found to be highly stable ferromagnetic half-metals, showing spin switching behavior. Transport calculations show that finite size clusters display spin filter property when coupled with Au electrodes on either side. I–Vb characteristics of all systems confirm the spin filter property, with Au–BzVCpVBz–Au displaying exceptionally high performance. In addition to spin filtering, the Au–BzFeCpFeBz–Au system also shows negative differential resistance (NDR). Compression causes an abrupt reduction in magnetic moment and a transition to a metallic phase, while stretching causes an increase in magnetic moment. Half-metallicity is preserved for modest amounts of stretching and compression.

Spin-glass-like behavior and related properties of aluminum-based Al−Y−RE−Ni (RE=Gd, Dy) amorphous alloys

Magnetic properties of the following alloys: Al87Y5Ni8, Al87Y4Gd1Ni8, Al87Gd5Ni8, Al87Y4Dy1Ni8, and Al87Dy5Ni8 were studied by means of magnetic, electrical transport, and heat capacity measurements. Low temperature isotherms, magnetization versus magnetic field, were analyzed numerically to obtain distribution of magnetic moments in the interacting clusters system. The resistivity ρr(T) and specific heat C(T)/T data indicate a spin-glass-like magnetic state for the alloys with RE=Gd or Dy. The obtained distribution of magnetic moments reveals the presence of small clusters of Ni separated by magnetic RE/Ni regions which exhibit a frustration. We found that in the Al87Y5Ni8 alloy, Ni atoms form only two types of magnetic clusters with about 70 or 300 atoms. Doping of the based system by RE atoms leads to a reduction of Ni clusters magnetic moment via breaking off Ni−Ni ferromagnetic interaction within the cluster. We also found that resistivity ρr(T) of the investigated amorphous alloys Al−Y−RE−Ni is almost T-independent between 200 and 300 K which is a result of strong atomic and magnetic disorder.

Half-metallic properties of the (1 1 0) surface of alkali earth metal monosilicides in the zinc blende phase

An all electron ab initio method was employed to study the electronic and magnetic properties of the (1 1 0) surface of alkaline-earth metal silicides: CaSi, SrSi and BaSi, in the zinc blende structure. The three surfaces are found to conserve the half-metallic properties of their bulk structures with a wide semiconducting energy gap in the spin-up channel. Half-metallic energy gap at the surfaces is small. In the CaSi surface it is of the order of kBT, which indicates that in the CaSi (1 1 0) a transition to a metallic state is possible due to temperature fluctuations. At the same time, the CaSi surface exhibits the strongest magnetic properties with 0.91 μB magnetic moment on the Si atom in the topmost layer and 0.21 μB magnetic moment on the Ca atom. In each of the three surfaces we observe a reduction of magnetic moments on the atoms in the subsurface layer and the enhancement of the magnetic moment on the atoms in the topmost layer, as compared with the properties of atoms in the bulk. An analysis of the calculated total and atom projected densities of states leads to a conclusion that the surface effects in the structures are short-range phenomena.

Computational Study of Magnetic and Vibrational Properties of Fe$_{4}$Al$_{11 - x}$ and Fe$_{4}$Al$_{11 - y}$Zn$_{y}$

We report first-principles calculations for Fe4Al11-x where 0 ≤ x ≤ 3 and for Fe4Al11-yZny for 0 ≤ y ≤ 1. We investigate the correlation of the magnetic and vibrational behavior with the density of states at the Fermi level. For Fe4Al11-x the magnitude of the magnetic moment correlates with the number of Fe in the chains. However we also find an intrinsic contribution to the magnetism associated with particular neighbor configurations, for Fe sites adjacent to the partially-occupied Al chains. The Fe content affects the density of states at the Fermi level by changing the magnitude of the spin majority, and as a result there are changing the magnetic properties. For Fe4Al11-yZny a reduction in the magnetization was observed with Zn substitution of Fe in the chains. There is a partial magnetic moment reduction for partial Zn substitution, but the magnetic moment is quenched when Zn fully substitutes for Fe in chain sites.

Magnetic structure of Fe-doped CoFe2O4probed by x-ray magnetic spectroscopies

The magnetic properties of iron-doped cobalt ferrite (Co${}_{1\ensuremath{-}x}$Fe${}_{2+x}$O${}_{4}$) (001) thin films grown epitaxially on MgO (001) substrates are investigated by superconducting quantum interference device magnetometry and soft x-ray magnetic linear and circular dichroisms. All Co${}_{1\ensuremath{-}x}$Fe${}_{2+x}$O${}_{4}$ (0.01 \ensuremath{\leqslant} $x$ \ensuremath{\leqslant} 0.63) samples have out-of-plane magnetic easy axes and large coercive fields, unlike Fe${}_{3}$O${}_{4}$, due to a large Co${}^{2+}$ orbital moment. The magnetic moments for those samples are significantly reduced from their bulk values; however, as $x$ increases, the magnetic moments tend nearer to their bulk values and increase more rapidly as $x$ approaches 1. This reduction in magnetic moment is attributed to spin canting among the Co${}^{2+}$ cations, owing to a small in-plane tensile strain in the film and to an increased antiferromagnetic alignment among all the cations caused by a partially inverse spinel cubic structure and the likely presence of antiphase boundaries. Our results show that small changes in stoichiometry can lead to significant changes in the magnetic moment of Co${}_{1\ensuremath{-}x}$Fe${}_{2+x}$O${}_{4}$, especially at large values of $x$.

Colloidal Stability of Magnetic Iron Oxide Nanoparticles: Influence of Natural Organic Matter and Synthetic Polyelectrolytes

The colloidal behavior of natural organic matter (NOM) and synthetic poly(acrylic acid) (PAA)-coated ferrimagnetic (γFe(2)O(3)) nanoparticles (NPs) was investigated. Humic acid (HA), an important component of NOM, was extracted from a peat soil. Two different molecular weight PAAs were also used for coating. The colloidal stability of the coated magnetic NPs was evaluated as a resultant of the attractive magnetic dipolar and van der Waals forces and the repulsive electrostatic and steric-electrosteric interactions. The conformational alterations of the polyelectrolytes adsorbed on magnetic γFe(2)O(3) NPs and their role in colloidal stability were determined. Pure γFe(2)O(3) NPs were extremely unstable because of aggregation in aqueous solution, but a significant stability enhancement was observed after coating with polyelectrolytes. The steric stabilization factor induced by the polyelectrolyte coating strongly dictated the colloidal stability. The pH-induced conformational change of the adsorbed, weakly charged polyelectrolytes had a significant effect on the colloidal stability. Atomic force microscopy (AFM) revealed the stretched conformation of the HA molecular chains adsorbed on the γFe(2)O(3) NP surface at pH 9, which enhanced the colloidal stability through long-range electrosteric stabilization. The depletion of the polyelectrolyte during the dilution of the NP suspension decreased the colloidal stability under acidic solution conditions. The conformation of the polyelectrolytes adsorbed on the NP surface was altered as a function of the substrate surface charge as viewed from AFM imaging. The polyelectrolyte coating also led to a reduction in magnetic moments and decreased the coercivity of the coated γFe(2)O(3) NPs. Thus, the enhanced stabilization of the coated maghematite NPs may facilitate their delivery in the groundwater for the effective removal of contaminants.

First principles study of structural, electronic and magnetic properties of Mg 1− xMn xTe alloys

Density functional FP-LAPW + lo calculations have been performed to study the structural, electronic and magnetic properties of Mg 1− x Mn x Te for compositional parameter x = 0.25, 0.50, 0.75 and 1. Our calculations reveal the occurrence of ferromagnetism in these compounds in which the transition-metal atom is ordered in a periodical way thereby interacting directly with the host atoms. Results extracted from electronic band structure and density of states (DOS) of these alloys show the existence of direct energy band gap for both majority- and minority-spin cases, while the total energy calculations confirm the stability of ferromagnetic state as compared to anti-ferromagnetic state. The total magnetic moment for Mg 1− x Mn x Te for each composition is found to be approximately 5 μ B, which indicates that the addition of Mn content does not affect the hole carrier concentration of the perfect MgTe compound. Moreover, the s–d exchange constant ( N 0 α) and p–d exchange constant ( N 0 β) are also calculated which are in accordance with a typical magneto-optical experiment. The estimated spin-exchange splitting energies originated by Mn 3d states energies, i.e. Δ X (s–d) and Δ X (p–d), show that the effective potential for minority-spin is more attractive than that of the majority-spin. Also, the p–d hybridization is found to cause the reduction of local magnetic moment of Mn and produce small local magnetic moments on the nonmagnetic Mg and Te sites.