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Pablo Nieves

Publications and source records attributed to Pablo Nieves.

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Development of a magnetic interatomic potential for cubic anti-ferromagnets: the case of NiO

Interatomic potentials are essential for molecular dynamics simulations of magnetic materials, yet incorporating magnetic features into potentials for complex antiferromagnets remains challenging. Nickel oxide (NiO), a prototypical cubic antiferromagnet, exemplifies this difficulty. Here we develop a methodology to integrate magnetic properties into interatomic potentials for cubic antiferromagnets by adding a magnetic Hamiltonian which includes both the Heisenberg exchange and N\'eel model. We apply this approach to NiO by constructing two potentials: one based on the Born model of ionic solids and another using a reference-free modified embedded atom method. Both potentials include magnetoelastic interactions and are validated against Density Functional Theory calculations, showing excellent agreement in mechanical and magnetic properties at zero temperature. These models enable large-scale simulations of magnetoelastic phenomena in antiferromagnets and open avenues for molecular dynamics studies involving coupled electric and magnetic fields in metal oxides.

cond-mat.mtrl-sci

Magnetoelasticity - magnetic structure interrelation - tetragonal MnPt system study

Magnetic materials represent an essential ingredient for the contemporary industry. Apart from common material parameters such as magnetocrystalline anisotropy, coercivity, or saturation magnetization, magnetoelastic behavior is vital for applications serving in various devices, e.g., in acoustic actuators, transducers, or sensors providing a desirable fast response and high efficiency with respect to applied magnetic field. Magnetoelastic properties have been studied for ferromagnetic 3d elements, or especially in high symmetry systems containing rare-earth elements to achieve higher values. Since, unlike for rare earth Laves phases, in the transition metals or alloys, these effects are very weak. Here, in contrast, we analyze the magnetoelastic behavior of antiferromagnetic tetragonal system MnPt, explaining the experimentally measured data based on the theoretical calculations and discussing the influence of the magnetic structure. Particularly, we inspect the origin of magnetocrystalline anisotropy energy, as well as the size and source of the isotropic and anisotropic parts of magnetoelastic (magnetostriction) coefficients.

cond-mat.mtrl-sci

Computational screening of Fe-Ta hard magnetic phases

In this work we perform a systematic calculation of the Fe-Ta phase diagram to discover novel hard magnetic phases. By using structure prediction methods based on evolutionary algorithms, we identify two new energetically stable magnetic structures: a tetragonal Fe$_3$Ta (space group 122) and cubic Fe$_5$Ta (space group 216) binary phases. The tetragonal structure is estimated to have both high saturation magnetization ($μ_0$M$_s$=1.14 T) and magnetocrystalline anisotropy (K$_1$=2.17 MJ/m$^3$) suitable for permanent magnet applications. The high-throughput screening of magneto-crystalline anisotropy also reveals two low energy metastable hard magnetic phases: Fe$_5$Ta$_2$ (space group 156) and Fe$_{6}$Ta (space group 194), that may exhibit intrinsic magnetic properties comparable to SmCo$_5$ and Nd$_2$Fe$_{14}$B, respectively.

cond-mat.mtrl-sci