A joint experimental and theoretical study on structural, electronic, and magnetic properties of MnGen− (n = 3–14) clusters

Abstract

A systematic structure and property investigation of MnGen− (n = 3–14) was conducted by means of density functional theory coupled with mass-selected anion photoelectron spectroscopy. This combined theoretical and experimental study allows global minimum and coexistence structures to be identified. It is found that the pentagonal bipyramid shape is the basic framework for the nascent growth process of MnGen− (n = 3–10), and from n = 10, the endohedral structures can be found. For n = 12, the anion MnGe12− cluster probably includes two isomers: a major isomer with a puckered hexagonal prism geometry and a minor isomer with a distorted icosahedron geometry. Specifically, the puckered hexagonal prism isomer follows the Wade–Mingos rules and can be suggested as a new kind of superatom with the magnetic property. Furthermore, the results of adaptive natural density partitioning and deformation density analyses suggest a polar covalent interaction between Ge and Mn for endohedral clusters of MnGe12−. The spin density and natural population analysis indicate that MnGen− clusters have high magnetic moments localized on Mn. The density of states diagram visually shows the significant spin polarization for endohedral structures and reveals the weak interaction between the Ge 4p orbital and the 4s, 3d orbitals of Mn.

Investigation of highly ferromagnetic Mn2Ge4 and Mn2Ge5 clusters via photoelectron spectroscopy and theoretical calculations

“…It could be obtained by adding one Mn atom to the symmetry plane of MnGe 4 − . 14 The ADE 1 and VDE 1 values of Mn 2 Ge 4 − (4A) are calculated to be 1.73 eV and 2.70 eV at the CCSD(T) level. Its theoretical VDE value (2.70 eV) is in excellent agreement with the experimental VDE value (2.69 eV).…”

“…The magnetic susceptibility data of Mn 2 Ge 4 and Mn 2 Ge 5 were calculated with the complete active space self-consistent field (CASSCF) methods 27 using the ORCA program. 28 Spin-orbit coupling effects were considered in the CASSCF (14,14) calculations. In order to further investigate the multiconfigurational effects, the extended DMRGCI approach 29 with large active spaces including the Ge 4s and/or 4p and Mn 3d/4s atomic orbitals (28 orbitals for Mn 2 Ge 4 À/0 and 27 orbitals for Mn 2 Ge 5 À/0 ) was conducted using the Block and PySCF programs.…”

“…In order to further investigate the magnetic properties of Mn 2 Ge 4 and Mn 2 Ge 5 , we calculated their magnetic susceptibility and magnetiztion values at the CASSCF (14,14) level. The spin-orbit coupling corrections were considered in the calculations, while the rotational modes were not considered.…”

“…6 In the last few decades, some theoretical and experimental studies have been conducted to explore the magnetic properties of Mn-doped germanium clusters and semiconductors. [7][8][9][10][11][12][13][14][15][16] Theoretical studies using the ab initio pseudopotential plane wave and relativistic density functional theory (DFT) methods suggested that the Mn@Ge 12 cluster was an icosahedral superatom with a high magnetic moment of 5 m B . 7,8 The electronic calculations of the Mn x Ge 1Àx alloy showed that the localized magnetic moments of Mn were about 3 m B /Mn.…”

“…It is found that the high magnetic moments of MnGe n À mainly originated from the Mn atoms. 14 In this work, we investigate the structures of Mn 2 Ge 4 À/0 and Mn 2 Ge 5 À/0 by anion photoelectron spectroscopy and theoretical calculations. Neutral Mn 2 Ge 4 and Mn 2 Ge 5 are found to be ferromagnetic with the magnetic moment as high as 10m B .…”