Structural, magnetic and electronic properties of Cu-Fe nanoclusters by density functional theory calculations

Abstract

We present results from density functional theory calculations referring to the magnetic properties of 13, 55, 147 and 309 atoms Cu-Fe icosahedral nanoclusters. Aiming in finding the nanocluster with the optimum magnetic moment (mВ) we explored the various sizes considering several compositions and atomic conformations. It came out that configurations with agglomerated Fe atoms inside the Cu-Fe nanoclusters and pure Cu surface shell are energetically favoured as demonstrated e.g. for the Cu49Fe6 with 2.3mВ compared to 2.1mВ of the Fe bcc. The highest magnetic moment, 3.6mВ, was found in the Cu12Fe case with the Fe atom located at the surface cell, while 3.18mВ was found for the Cu297Fe12 in a similar configuration having Fe atoms surrounded by Cu that occupy the surface shell's edges. The magnetic moment is mainly due to Fe's spin up-down electronic density of states difference close to the Fermi level (EF). In particular, the Spin-up Fe d electronic density of states are fully occupied yielding wavefunctions with homogeneous change distribution while the Spin-down is almost unoccupied exhibiting dangling bonding states close to EF. These results could be used for the design of environmental sustainable smart alloys with superior magnetic properties e.g. by depositing Fe or FeCu on Cu nanoclusters or including new elements that provide the possibility of keeping the Fe Spin up-down electronic occupation difference close to EF.

Fe–Co magnetic nanoclusters by density functional theory calculations

“…These DFT data agree with experimental studies that the Fe/Cu(111) MM stands within the large ICOs and the bulk MM values [6][7][8][9][10]. Indeed, when growing Fe thin films on non-magnetic substrates like Cu results in an fcc tetragonal distorted (fct) structure depending on the film thickness showing higher local Fe MM up to 2.5-2.7 μB on Cu(100) and 3.3 μB on Cu(111) than the Fe bcc (2.1-2.15 μB) [7][8][9][10].…”

“…The Co surface atoms of Cu54Fe local MM varies from 1.84 to 1.87 μB while the core Co atom has on the average 1.6 μB that is smaller than the Co bcc (1.7 μB). This Fe atom's higher local MM at the surface was also found for the Cu49Fe case[6].Furthermore, we study several configurations in theCo49Fe6 clusters by substituting six Co atoms with Fe atoms: (a) at the cluster's edge (−4.163 eV), (b) side (covering one surface side triangle, −4.159 eV) and (c) the half 1rst shell positions (−4.157 eV) revealing the Edge Co49Fe6 as the energetically favoured. In addition, the Edge Co49Fe6 exhibits the highest local Fe MM (2.92 μB) compared to the Side (2.87 μB) and 1st shell's (2.50 μB) configurations in line with the Cu49Fe cases [6].…”

Parametric aqueous electrodeposition study and characterization of Fe–Cu films

“…Importantly, films with a 6 at% Fe exhibit ferromagnetic behavior albeit with a very low saturation magnetization (~4 emu g -1 ). This is probably due to the occurrence of phase separation since fully alloyed fcc films with 6 at% Fe are typically paramagnetic at room temperature [13], although an enhanced magnetization is expected at low temperature for fcc-CuFe clusters with very small sizes [45]. Note that a 2-3% bcc-Fe (not detectable by XRD) would be enough to give this small value of M S .…”

Exploration of the Structural, Electronic and Tunable Magnetic Properties of Cu4M (M = Sc-Ni) Clusters

“…Experimental and theoretical research has manifested that the introduction of a dopant atom into a small cluster can considerably change the nature of the host cluster. Copper clusters doped with an impurity atom have been actively pursued to tailor the desired structural, electronic, magnetic and optical properties for potential applications in solid state chemistry, materials science, nanotechnology and microelectronics [ 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 ]. For example, the bimetallic Cu n Pd m ( ) clusters are more stable than the monometallic particles with the same size [ 35 ].…”

“…The Ti- and V-doping dramatically improves the adsorption of copper clusters on NO molecules, but it does not affect the O 2 adsorption probability significantly [ 40 ]. The Cu-Fe icosahedral nano-clusters exhibit larger magnetic moments than the Fe thin films and bulk systems [ 41 ]. The Cu n Se clusters are the perfect candidate for renewable energy sources in the photocatalysis field [ 42 ].…”