We have examined the electronic structure and bonding of the Mn2 molecule through multireference variational calculations coupled with augmented quadruple correlation consistent basis sets. The Mn atom has a S6(4s23d5) ground state with its first excited state, D6(4s13d6), located 2.145 eV higher. For all six molecular states Σ1g+, Σ3u+, Σ5g+, Σ7u+, Σ9g+, and Σ11u+(1) correlating to Mn(S6)+Mn(S6), and for six undecets, i.e., Π11u, Σ11g+, Δ11g, Δ11u, Σ11u+(2), and Π11g with end fragments Mn(S6)+Mn(D6), complete potential energy curves have been constructed for the first time. We prove that the bonding in Mn2 dimer is of van der Waals type. The interaction of two Mn S6 atoms is hardly influenced by the total spin, as a result the six Σ states, singlet (Σ1g+) to undecet (Σ11u+(1)), are in essence degenerate packed within an energy interval of about 70 cm−1. Their ordering follows the spin multiplicity, the ground state being a singlet, X Σ1g+, with binding energy De (D0)≈600 (550)cm−1 at re≈3.60 A. The six u...

First principles study of the electronic structure and bonding of Mn2

Optical and structural properties of manganese sulfide thin films

Large coercivity and small exchange bias in Mn3O4 / MnO nanoparticles

We investigate the stability of the collinear ferromagnetic state in kinetic exchange models for (III,Mn)V semiconductors with randomly distributed Mn ions. Our results suggest that noncollinear ferromagnetism is common to these semiconductor systems. The instability of the collinear state is due to long-range fluctuations involving a large fraction of the localized magnetic moments. We address conditions that favor the occurrence of noncollinear ground states and discuss unusual behavior that we predict for the temperature and field dependence of its saturation magnetization.

Noncollinear Ferromagnetism in (III,Mn)V Semiconductors

The relation between magnetic properties and microscopic structure for a metal/semiconductor system is described. Cobalt films on a CoSi interface possess an in-plane easy axis of magnetization as the result of magnetocrystalline anisotropy of the Co∕CoSi interface. On a Si(111)-7×7 surface, direct evidence for the formation of CoSi2 compounds at the interface was found by the appearance of doubled spot defects in scanning tunneling microscopic images. The interfacial effects cause the easy axis of magnetization of a Co∕Si interface to be canted out of plane.

Microscopic interfacial structures and magnetic properties of ultrathin Co∕Si(111) films

This paper presents a review of the electronic, magnetic and spectroscopic properties of manganese (Mn)-based nanostructures. In the last few years a variety of techniques have been used to prepare mesoscopic transition-metal islands and novel effects associated with the electronic structure in nanoscale systems have been reported. Mn in the atomic configuration possesses a moment as high as 5μB so it should be very interesting to dope semiconductors with Mn for spin injection or to use Mn itself for permanent magnets. In this paper the introduction (section 1) focuses mainly on metallic Mn nanostructures which are the core of this review. Nevertheless we try to present a general overview of various kinds of Mn structures as well as several theoretical methods with their own limitations to handle the corresponding problems. More precisely, section 2 outlines a variety of bulk, surface, interface and cluster structures with their resulting magnetism as far as Mn is concerned. Actually, in these past two decades, considerable interest has been devoted to Mn nanostructures deposited on various metallic substrates (section 3). Because of its exotic structural and magnetic properties, Mn is indeed an interesting candidate for ultra-thin film growth as it is expected to accept different local configurations. Experimentally, one may attempt to stabilize normally high-temperature phases of Mn by epitaxial growth on a suitable substrate. Specifically, we shall point out the frequently occurring, important situation of magnetically stabilized surface alloys. Next (section 4) we first focus on spectroscopic properties of Mn compounds as well as Mn adsorbates upon graphite and other substrates both experimentally and theoretically. Moreover, we recall a few remarks about Mn impurities with respect to the Kondo problem and also with respect to semiconductors and spintronics. In the latter field, practical applications actually require room-temperature Mn ferromagnetism which is not that easy to obtain. Finally, in section 5, we point out that a given Mn nanostructure generally exhibits a non-collinear (NCL) structure which is often the most stable one among all the collinear and NCL ones. This fact explains why constrained collinear calculations have often disagreed with the corresponding experimental data. Section 6 is devoted to a short discussion where we recall a few important points that have been developed in this paper.

https://iopscience.iop.org/article/10.1088/0034-4885/65/11/203/pdf

J C Parlebas

Papers

Electronic, magnetic and spectroscopic properties of manganese nanostructures