Mn Atom Site Research Articles

Exploring the Relationship between the Structural Characteristics and Mechanical Behavior of Multicomponent Fe-Containing Phases: Experimental Studies and First-Principles Calculations.

A comprehensive understanding of the structural characteristics and mechanical behavior of Fe-containing phases is important for high-Fe-level Al-Si alloys. In this paper, the crystal characteristics, thermal stability, thermophysical properties and mechanical behavior of multicomponent α-AlFeMnSi and α-AlFeMnCrSi phases are investigated by experimental studies and first-principles calculations. The results indicate that it is easier for Fe and Cr to substitute the Mn-12j site in α-AlMnSi in thermodynamics; Cr is preferred to Fe for substituting Mn-12j/k sites due to its lower formation enthalpy after single substitutions at Mn atom sites. The α-AlFeMnCrSi phase shows higher thermal stability, modulus and intrinsic hardness and a lower volumetric thermal expansion coefficient at different temperatures due to the strong chemical bonding of Si-Fe and Si-Cr. Moreover, the α-AlFeMnCrSi phase has a higher ideal strength (10.65 GPa) and lower stacking fault energy (1.10 × 103 mJ/m2). The stacking fault energy evolution of the different Fe-containing phases is mainly attributed to the differential charge-density redistribution. The strong chemical bonds of Si-Fe, Si-Mn and Si-Cr are important factors affecting the thermophysical and mechanical behaviors of the α-AlFeMnCrSi phase.

Atomistic simulation of trivalent ions doped in the hexagonal LuMnO3 ferroelectric phase

The interatomic potentials for multiferroic hexagonal LuMnO3 (h-LMO) in its ferroelectric (FE) phase was obtained for empirical fitting procedure and applied to study the effects of a series of trivalent metal and rare-earth dopants on its structural and ferroelectric distortions. The potential parameters found accurately reproduce lattice parameters (error below 0.3%), interatomic distances, pressure effect on the lattice parameters, and tilting angles of the MnO5 polyhedron. We investigated doping at Mn, Lu1 and Lu2 atom sites. It was found that the doped Mn atom site is the most energetically advantageous site for both the metal (Al, Ga, Fe and Cr) and rare-earth (La, Nb, Sm, Eu, Gd, Ho, Er, Yb, Y and Sc) atoms studied. The M-O3/O4 distances decrease when the Mn3+ ion site is doped by trivalent metal ions. The effects on the FE distortion of the material under doping and changes in the tilting angle of the M/MnO5 polyhedron were analyzed.

Composition-tuned magneto-optical Kerr effect in L10-MnxGa films with giant perpendicular anisotropy

We report the large polar magnetooptical Kerr effect in L10-MnxGa (0.76 ⩽ x ⩽ 1.29) epitaxial films with giant perpendicular magnetic anisotropy. The Kerr rotation is enhanced by a factor of up to 2.5 by decreasing Mn atomic concentration, which most likely arises from the variation of the effective spin–orbit coupling strength, compensation effect of magnetic moments at different Mn atom sites, and overall strain. A significant tuning effect of composition is also observed on Kerr ellipticity and complex Kerr angle (including the magnitude and phase angle). The good epitaxial compatibility with semiconductors, moderate coercivity of 4.6–9.7 kOe, large Kerr rotation of up to 0.10°, high reflectivity of 35%–55% in a wide wavelength range of 400 ~ 850 nm, and giant magnetic anisotropic field of up to 140 kOe together make these L10-MnxGa films promising for scientific and technological applications in spintronics and terahertz-frequency magnetooptical modulators.

NO adsorption on nickel and nickel–manganese bimetallic clusters: A density functional study

Using first principle calculations, geometry, binding energies and magnetic moments of Nin and Nin−1Mn (n=2−8) clusters are reported. The stability of the clusters is discussed in terms of binding energy. The relative stability is examined using the second order energy difference. Structures of Nin and Nin−1Mn clusters are similar. The bimetallic clusters have higher magnetic moments. We have investigated the adsorption of NO molecule on these clusters since it is one of the crucial steps for activation of catalytic oxidation/reduction process. The adsorption of NO molecule is energetically more favored on bimetallic clusters. NO molecule prefers to be adsorbed near the Mn atom site. Bader charge analysis shows that electrons are transferred from metal cluster to NO molecule.

Magnetic behavior of LaMn2(Si(1−x)Gex)2 compounds characterized by magnetic hyperfine field measurements

The temperature dependence of the magnetic hyperfine field (Bhf) at Mn atom sites was measured in LaMn2(Si(1−x)Gex)2, with 0 ≤ x ≤ 1, compounds with perturbed γ−γ angular correlation spectroscopy using 111In(111Cd) as probe nuclei in the temperature range from 20 K to 480 K. The results show a transition from antiferromagnetic to ferromagnetic ordering for all studied compounds when Ge gradually replaces Si and allowed an accurate determination of the Néel temperature (TN) for each compound. It was observed that TN decreases when Ge concentration increases. Conversely, the Curie temperature increases with increase of Ge concentration. This remarkable change in the behavior of the transition temperatures is discussed in terms of the Mn-Mn distance and ascribed to a change in the exchange constant Jex.

Implantation of 111In in the Heusler alloys Pd2MnZ (Z=Sn,Sb,Ge,In) following heavy ion nuclear reactions: measurement of magnetic hyperfine field using PAC spectroscopy

Ion implantation of the recoil 111In nuclei following heavy ion nuclear reactions 108Pd(7Li,4n)111In and 108Pd(6Li,3n)111In has been used to implant 111In probes in the Heusler alloys Pd2MnZ(Z=Sn,Sb,Ge,In). Perturbed Angular Correlation method was used to study the hyperfine magnetic field in these alloys. Direct implantation of 111In probe nuclei was used to great advantage in the present case resulting in large implantation efficiency. Only a few hours of irradiation time with moderate beam current of the order of 400-500 nA resulted in sufficient implanted 111In activity on the sample for good quality measurements. The hyperfine field was measured at 111In probe nuclei substituting Mn and Z sites as a function of temperature. The fraction of 111In nuclei occupying Mn atom sites was found to increases with the annealing of sample at higher temperatures.

Implantation of 111In-probe Nuclei with Nuclear Reactions 108Pd(6, 7Li, xn)111In using Pelletron Tandem Accelerator: Study of Local Magnetism in Heusler Alloys

Perturbed Angular Correlation method has been used to study the hyperfine magnetic field in the Heusler alloy Pd2MnSb(Sn). Ion implantation of the recoil 111In nuclei following heavy ion nuclear reactions 108Pd(7Li, 4n)111In and 108Pd(6Li, 3n)111In has been used to great advantage in the present case resulting in large implantation efficiency. Only a few hours of irradiation time with moderate beam current of the order of 400–500 nA resulted in sufficient implanted 111In activity on the sample for good quality measurements. The hyperfine field was measured at 111Cd probe nuclei substituting Mn and Sb(Sn) sites as a function of temperature. The fraction of 111Cd nuclei occupying Mn atom sites was found to increases with the annealing of sample at higher temperatures.