Electronic structure and magnetic properties in T2AlB2 ( T =Fe, Mn, Cr, Co, and Ni) and their alloys

Abstract

The electronic structure and intrinsic magnetic properties of Fe2AlB2-related compounds and their alloys have been investigated using density functional theory. For Fe2AlB2, the crystallographic a axis is the easiest axis, which agrees with experiments. The magnetic ground state of Mn2AlB2 is found to be ferromagnetic in the basal ab plane, but antiferromagnetic along the c axis. All 3d dopings considered decrease the magnetization and Curie temperature in Fe2AlB2. Electron doping with Co or Ni has a stronger effect on the decreasing of Curie temperature in Fe2AlB2 than hole doping with Mn or Cr. However, a larger amount of Mn doping on Fe2AlB2 promotes the ferromagnetic to antiferromagnetic transition. A very anisotropic magnetoelastic effect is found in Fe2AlB2: the magnetization has a much stronger dependence on the lattice parameter c than on a or b, which is explained by electronic-structure features near the Fermi level. Dopings of other elements on B and Al sites are also discussed.

Designing of magnetic MAB phases for energy applications

“…in the ESI †) with the absolute value of at least one MAE greater than 1.0 MJ m À3 . For instance, the MAE of Fe 2 AlB 2 has been evaluated by different groups,21,22,26 and our result of À1.14 MJ m À3 is in good agreement with the experimental measurements of À0.9 MJ m À3 at 50 K by Barua 22 and theoretical calculation À1.34 MJ m À3 by Ke. 26 In the newly predicted compounds, the MAB phase Mn 4 PtB 4 has the largest MAE as 13.498, 11.948 and À1.550 MJ m À3 for K 001-010 , K 001-100 and K 010-100 .…”

“…Moreover, Fe 2 AlB 2 was found to be a promising magnetocaloric material exhibiting an interesting MCE, 20 with the ordering temperature around 300 K conrmed by experimental 21,22 and theoretical studies. [23][24][25] Ke et al 26 investigated the intrinsic properties of Fe 2 AlB 2 , and found a MAE as large as À1.34 MJ cm À3 , in good agreement with the experiments. 22 Recently, Cr 4 AlB 4 with a novel structure of MAB phase has been synthesized consistent with the theoretical calculations.…”

“…65 This applies particularly to Mn-based compounds, as revealed by a recent work that the energy landscape of the convex hull is drastically changed aer considering the magnetic ground state. 66 According to the literature, the 212-type Mn 2 AlB 2 is observed to display an AFM magnetic ground state with Néel temperature about 390 K, 26,67,68 thus we performed extensive calculations on the predicted 212type MAB compounds. As summarized in Table S2, † 15 out of 54 magnetic compounds prefer AFM magnetic congurations, including not only Mn-based but also Fe-and Co-based compounds.…”

First-Principles Prediction of a Room-Temperature Ferromagnetic Janus VSSe Monolayer with Piezoelectricity, Ferroelasticity, and Large Valley Polarization

“…After confirming the stability of magnetic Janus VSSe monolayers at an elevated temperature, we further move to check if the ferromagnetic could survive at room temperature. The Curie temperature T C can be estimated by the mean-field approximation (MFA) and Heisenberg model [24,25].…”

Near room temperature antiferromagnetic ordering with a potential low-dimensional magnetism in AlMn2B2

“…In addition, some inconsistencies between bulk and local probe magnetic measurements in the Al(Fe 1−x Mn x ) 2 B 2 were observed. A later first principle calculation suggested that AlMn 2 B 2 should be an anti-ferromagnetic compound [6]. In a recent powder neutron study, AlMn 2 B 2 is identified as a ceramic AFM compound [7] with Neel temperature around 390 K. A study of lattice parameters variation from room temperature to 1200 K revealed that there is a change in anisotropy nature in a and c lattice parameters around 450 K and a local minimum in b lattice parameters around 400 K [8].…”