Magnetic coupling in neutral and charged Cr2, Mn2, and CrMn dimers

Abstract

Theoretical ab initio studies of neutral, cationic and anionic Cr 2 , Mn 2 , and CrMn dimers have been carried out to explore the progression of magnetic coupling with the number of electrons. It is shown that while Cr 2 and Cr 2 Ϫ have antiferromagnetically coupled atomic spins, Cr 2 ϩ has a ferromagnetic ground state closely followed by an antiferromagnetic state. On the other hand, all Mn 2 dimers are ferromagnetic, irrespective of the charge. The neutral CrMn is ferrimagnetic while the charged CrMn are antiferromagnetic. In all cases, the charged dimers are found to be more stable than the neutral ones. The results are compared with available calculations and experiments and the difficulties associated with theoretical description and the experimental interpretations are discussed.

Magnetism and the electronic correlations in Mn clusters

“…However, Nesbet's prediction was seemingly confirmed by ESR studies of a Mn 2 molecule in low temperature (Ar, Kr, and Xe) matrices [1]. Very recent and extensive first-principles density-functional studies have confirmed, in odds with experimental results, Harris and Jones prediction of a ferromagnetic Mn dimer [8][9][10][11][12][13]. Current opinion is that van der Waals interaction is holding together the manganese dimer.…”

A computational investigation of boron-doped chromium and chromium clusters by density functional theory

“…The local magnetic moments of the Cr sites also appear ferromagnetic or antiferromagnetic aligment for n≥4. In Cr n B clusters (n=4, 5,6,8,9), the total magnetic moments are enhanced compared to that of corresponding Cr n clusters, respectively. For Cr 7 B clusters, the total magnetic moment is reduced compared to Cr 7 cluster.…”

“…Its 3d 5 4s 1 electronic configuration results in strong d-d bonding in dimer with short bond length (1.68 Å) [1−4], while bulk chromium is antiferromagnetic with a body-centered-cubic (bcc) structure (nearest Cr-Cr distance: 2.50 Å) [5]. In last decade, the bonding nature and electronic structure in small chromium clusters have been studied by experimental and theoretical methods [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. The geometric and magnetic properties of chromium clusters have been performed by density functional theory (DFT) [20,21].…”

Nachweis maximaler Spinpolarisation in Chromdimerkationen durch zirkularen magnetischen Röntgendichroismus

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[24,25] Wirz eigen hier experimentell, dass Cr 2 + in der Tate inen Hochspingrundzustand besitzt und sich damit in der elektronischen Konfiguration deutlich von Cr 2 unterscheidet. Hierbei nutzen wir den Effekt des magnetischen zirkularen Rçntgendichroismus (XMCD) in der L 2,3 (2p!3d)-Rumpfanregung,d essen Vermessung eine Standardmethode zur Bestimmung der Magnetisierung von Festkçrpern oder Dünnschichtsystemen der 3d-Übergangsmetallverbindungen darstellt, von uns hier aber auf freie Cr 2 + -Ionen in einer linearen Tieftemperatur-Quadrupolfalle in einem starken Magnetfeld [26][27][28][29][30][31] angewendet wird.

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