Competing structural and magnetic effects in small iron clusters

Electronic ground states of Fe2+ and Co2+ as determined by x-ray absorption and x-ray magnetic circular dichroism spectroscopy

“…[13][14][15][16][17][18][19][20][21][22][23] Experimental data, on the other hand, has resisted to yield a conclusive picture. [5][6][7][8][9][10][11][12] From a different point of view, the possibility of aligning molecules in magnetic fields 24,25 and the question of the fundamental limits of the magnetic anisotropy energy that is responsible for a preferred axis of alignment of the magnetic moment naturally lead to diatomic molecules of 3d transition elements and their complexes.…”

Electron Correlation Effects in the Fe Dimer

“…[15][16][17][18][19][20] As a detailed account of the results obtained in these studies cannot be given here, we refer the reader to the most recent articles and references therein. [18][19][20] Most of these works are based on density functional theory (DFT) employing the local density approximation (LDA) or different kinds of the generalized gradient approximation (GGA) for the calculation of the exchange-correlation energy, E xc . It turns out that, independent of the specific implementation of DFT and the details of the computational scheme, all these studies, including the early configuration interaction (CI) calculations, 16 find a 7 ∆ u ground state with a magnetic moment of 6 µ B and a formal electronic occupation of 3d 14 4s 2 .…”

First principles studies of Fe m Ir n (2 ≤ m + n ≤ 4) nano clusters

“…It is a known fact that for larger clusters, role of quantum fluctuations beyond the mean field and appearance of non-collinear spin configurations should be considered for accurate results (Ojeda et al 1999). However, for the smaller clusters considered in the present study, GGA is considered to deliver accurate results as has been shown by previous studies (Rollmann et al 2006;Longo et al 2008). Ab initio total energy calculations by Rollmann et al (2006) has shown that relaxation in small Fe clusters leads to stabilization of collinear magnetic structures.…”

“…However, for the smaller clusters considered in the present study, GGA is considered to deliver accurate results as has been shown by previous studies (Rollmann et al 2006;Longo et al 2008). Ab initio total energy calculations by Rollmann et al (2006) has shown that relaxation in small Fe clusters leads to stabilization of collinear magnetic structures. In another study by Longo et al (2008), also the non-collinear magnetic order is not found to exist in FeMn clusters.…”

“…The high surface to volume ratio of these clusters gives rise to fewer bonds per metal atom and hence frees up non-bonded valence electrons, leading to enhanced magnetic moments if left unpaired. Therefore, the magnetic moments in these clusters are very much sensitive to the geometry of the cluster and the chemical environment (Rao et al 1990;Rollmann et al 2006;Longo et al 2008). In this scenario, clusters of transition metals attract particular attention as they are known to display enhanced magnetic moments relative to the bulk counterparts, hence are relevant candidates for magnetic storage devices.…”