Abstract
We present ab-initio density-functional calculations of the structural, magnetic, and chemical properties of cobalt–copper clusters (1 nm in size) with two to six atoms. We applied several search methods to find the most stable configurations for all stoichiometries. Particular attention is given to the relation between the geometric and magnetic structures. The clusters behavior is basically governed by the Co–Co interaction and to a lesser extent by the Co–Cu and Cu–Cu interactions. A tendency for Co-clumping is observed. Such information is quite relevant for segregation processes found in bulk Co–Cu alloys. For a given cluster size, magnetic moments increase mostly by 2μB per Co-substitution coming from the cobalt d-states, while for some cases s-electrons give rise to itinerant magnetism. Magnetic moment results are also consistent with the ultimate jellium model because of a 2D to 3D geometrical transition. The chemical potential indicates less chemical stability with the Co atoms, while the molecular hardness can be linked mostly to the ionization potential for these small clusters.
Similar content being viewed by others
References
Bagno P, Jepsen O, Gunnarsson O (1989) Ground-state properties of third-row elements with nonlocal density functionals. Phys Rev B 40:1997–2000
Baibich MN, Broto JM, Fert A, Nguyenvan Dau F, Petroff F, Etienne P, Creuzet G, Friederich A, Chazelas J (1988) Giant magnetoresistance of (001)Fe/(001)Cr magnetic superlattices. Phys Rev Lett 61:2472–2475
Bakonyi I, Simon E, Tóth BG, Péter L, Kiss LF (2009) Giant magnetoresistance in electrodeposited Co–Cu/Cu multilayers: origin of the absence of oscillatory behavior. Phys Rev B 79:174421
Becke AD (1988) Density-functional exchange-energy approximation with correct asymptotic behavior. Phys Rev A 38:3098–310
Berkowitz AE, Mitchell JR, Carey MJ, Young AP, Zhang S, Spada FE, Parker FT, Hutten A, Thomas G (1992) Giant magnetoresistance in heterogeneous Cu–Co alloys. Phys Rev Lett 68:3745–3748
Castro M, Jamorski C, Salahub DR (1997) Structure, bonding, and magnetism of small Fe n , Co n , and Ni n clusters, n ≤ 5. Chem Phys Lett 271:133–142
Cezar JC, Tolentino HC, Knobel M (2003) Structural, magnetic, and transport properties of Co nanoparticles within a Cu matrix. Phys Rev B 68:054404
Chattaraj PK, Liu GH, Parr RG (1995) The maximum hardness principle in the Gyftopoulos–Hatsopoulos three-level model for an atomic or molecular species and its positive and negative ions. Chem Phys Lett 237:171–176
Datta S, Kabir M, Ganguly S, Sanyal B, Saha-Dasgupta T, Mookerjee A (2007) Structure, bonding, and magnetism of cobalt clusters from first-principles calculations. Phys Rev B 76:014429
Dong CD, Gong XG (2008) Magnetism enhanced layer-like structure of small cobalt clusters. Phys Rev B 78:020409
Fan HJ, Liu CW, Liao MS (1997) Geometry, electronic structure and magnetism of small Co n (n = 2–8) clusters. Chem Phys Lett 273:353–359
Fan X, Mashimo T, Huang X, Kagayama T, Chiba A, Koyama K, Motokawa M (2004) Magnetic properties of Co–Cu metastable solid solution alloys. Phys Rev B 69:094432
Ferrando R, Jellinek J, Johnston RL (2008) Nanoalloys: from theory to applications of alloy clusters and nanoparticles. Chem Rev 108:845–910
Ganguly S, Kabir M, Datta S, Sanyal B, Mookerjee A (2008) Magnetism in small bimetallic Mn–Co clusters. Phys Rev B 78:014402
Ghanty TK, Banerjee A, Chakrabarti A (2010) Structures and the electronic properties of Au19X clusters (X = Li, Na, K, Rb, Cs, Cu, and Ag). J Phys Chem C 114:20–27
Ghosh SK, Grover AK, Chowdhury P, Gupta SK, Ravikumar G, Aswal DK, Senthil Kumar M, Dusane RO (2006) High magnetoresistance and low coercivity in electrodeposited Co/Cu granular multilayers. Appl Phys Lett 89:132507
Hales DA, Su CX, Lian L, Armentrout PB (1994) Collision-induced dissociation of Co + n (n = 2–18) with Xe: bond energies of cationic and neutral cobalt clusters, dissociation pathways, and structures. J Chem Phys 100:1049–1057
Hickey BJ, Howson MA, Musa SO, Wiser N (1995) Giant magnetoresistance for superparamagnetic particles: melt-spun granular CuCo. Phys Rev B 51:667–669
Jamorski C, Martínez A, Castro M, Salahub DR (1997) Structure and properties of cobalt clusters up to the tetramer: a density-functional study. Phys Rev B 55:10905–10921
Jaque P, Toro-Labbé A (2002) Characterization of copper clusters through the use of density functional theory reactivity descriptors. J Chem Phys 117:3208–3218
Jaque P, Toro-Labbé A (2004) The formation of neutral copper clusters from experimental binding energies and reactivity descriptors. J Phys Chem B 108:2568–2574
Ju SP, Lo YC, Sun SJ, Chang JG (2005) Investigation on the structural variation of CoCu nanoparticles during the annealing process. J Phys Chem B 109:20805–20809
Kabir M, Mookerjee A, Bhattacharya AK (2004a) Copper clusters: electronic effect dominates over geometric effect. Eur Phys J D 31:477–485
Kabir M, Mookerjee A, Bhattacharya AK (2004b) Structure and stability of copper clusters: a tight-binding molecular dynamics study. Phys Rev A 69:043203
Knorr N, Schneider MA, Diekhöner L, Wahl P, Kern K (2002) Kondo effect of single Co adatoms on Cu surfaces. Phys Rev Lett 88:096804
Kohn W, Becke AD, Parr RG (1996) Density functional theory of electronic structure. J Phys Chem 100:12974–12980
Kolehmainen J, Häkkinen H, Manninen M (1997) Metal clusters on an inert surface: a simple mode. Z Phys D 40:306–309
Koskinen M, Lipas PO, Manninen M (1995) Electron-gas clusters: the ultimate jellium model. Z Phys D 35:285–297
Kresse G, Furthmüller J (1996a) Efficiency of ab-initio total energy calculations for metals and semiconductors using a plane-wave basis set. Comput Mat Sci 6:15–50
Kresse G, Furthmüller J (1996b) Efficient iterative schemes for ab-initio total-energy calculations using a plane-wave basis set. Phys Rev B 54:11169–11186
Kresse G, Hafner J (1993) Ab-initio molecular dynamics for liquid metals. Phys Rev B 47:558–561
Kresse G, Hafner J (1994) Norm-conserving and ultrasoft pseudopotentials for first-row and transition-elements. J Phys Condens Matter 6:8245–8257
Kresse G, Joubert D (1999) From ultrasoft pseudopotentials to the projector augmented-wave method. Phys Rev B 59:1758–1775
Kübbler J (1981) Magnetic moments of ferromagnetic and antiferromagnetic bcc and fcc iron. Phys Lett A 81:81–83
Kullie O, Zhang H, Kolb D (2008) Relativistic and non-relativistic local-density functional, benchmark results and investigation on the dimers Cu2, Ag2, Au2, Rg2. Chem Phys 351:106–110
Leopold DG, Lineberger WC (1986) A study of the low-lying electronic states of Fe2 and Co2 by negative ion photoelectron spectroscopy. J Chem Phys 85:51–55
Lu QL, Zhu LZ, Ma L, Wang GH (2005) Magnetic properties of Co/Cu and Co/Pt bimetallic clusters. Chem Phys Lett 407:176–179
Mejía-López J, García G, Romero AH (2009) Physical and chemical characterization of Pt12−n Cu n clusters via ab-initio calculations. J Chem Phys 131:044701
Miranda MGM, Estévez-Rams E, Martínez G, Baibich MN (2003) Phase separation in Cu90Co10 high-magnetoresistance materials. Phys Rev B 68:014434
Miranda MGM, da Rosa AT, Hinrichs R, Golla-Schindler U, Antunes AB, Martínez G, Estévez-Rams E, Baibich MN (2006) Spinodal decomposition and giant magnetoresistance. Phys B 384:175–178
Néel N, Kröger J, Berndt R, Wehling TO, Lichtenstein AI, Katsnelson MI (2008) Controlling the Kondo effect in CoCu n clusters atom by atom. Phys Rev Lett 101:266803
Parkin SSP, More N, Roche KP (1990) Oscillations in exchange coupling and magnetoresistance in metallic superlattice structures: Co/Ru, Co/Cr, and Fe/Cr. Phys Rev Lett 64:2304–2307
Parr RG, Pearson RG (1983) Absolute hardness: companion parameter to absolute electronegativity. J Am Chem Soc 105:7512–7516
Parr RG, Yang M (1984) Density functional approach to the frontier-electron theory of chemical reactivity. J Am Chem Soc 106:4049–4050
Perdew JP (1986) Density-functional approximation for the correlation energy of the inhomogeneous electron gas. Phys Rev B 33:8822–8824
Perdew JP, Wang Y (1986) Accurate and simple density functional for the electronic exchange energy: generalized gradient approximation. Phys Rev B 33:8800–8802
Perdew JP, Wang Y (1992) Accurate and simple analytic representation of the electron-gas correlation energy. Phys Rev B 45:13244–13249
Perdew JP, Burke K, Ernzerhof M (1996a) Generalized gradient approximation made simple. Phys Rev Lett 77:3865–3868
Perdew JP, Burke K, Wang Y (1996b) Generalized gradient approximation for the exchange-correlation hole of a many-electron system. Phys Rev B 54:16533–16539
Quaas N, Wenderoth NM, Weismann A, Ulbrich RG, Schönhammer K (2004) Kondo resonance of single Co atoms embedded in Cu(111). Phys Rev B 69:201103
Rabedeau TA, Toney MF, Marks RF, Parkin SSP, Farrow RFC, Harp GR (1993) Giant magnetoresistance and Co-cluster structure in phase-separated Co–Cu granular alloys. Phys Rev B 48:16810–16813
Rastei MV, Heinrich B, Limot L, Ignatiev PA, Stepanyuk VS, Bruno P, Bucher JP (2007) Size-dependent surface states of strained cobalt nanoislands on Cu(111). Phys Rev Lett 99:246102
Rogan J, Ramírez M, Muñoz V, Valdivia JA, García G, Ramírez R, Kiwi M (2009) Diversity driven unbiased search of minimum energy cluster configurations. J Phys Condens Matter 21:084209
Rohlfing EA, Valentini JJ (1986) UV laser excited fluorescence spectroscopy of the jet-cooled copper dimer. J Chem Phys 84:6560–6566
Wang F, Liu W (2005) Benchmark four-component relativistic density functional calculations on Cu2, Ag2, and Au2. Chem Phys 311:63–69
Wang CS, Klein BM, Krakauer H (1985) Theory of magnetic and structural ordering in iron. Phys Rev Lett 54:1852–1855
Wang JL, Wang G, Chen X, Lu W, Zhao J (2002) Structure and magnetic properties of Co–Cu bimetallic clusters. Phys Rev B 66:014419
Wang H, Khait YG, Hoffmann MR (2005) Low-lying quintet states of the cobalt dimer. Mol Phys 103:263–268
Xiao JQ, Jiang JS, Chien CL (1992) Giant magnetoresistance in nonmultilayer magnetic systems. Phys Rev Lett 68:3749–3752
Yang M, Jackson KA, Koehler C, Frauenheim T, Jellinek J (2006) Structure and shape variations in intermediate-size copper clusters. J Chem Phys 124:024308
Zimmermann CG, Yeadon M, Nordlund K, Gibson JM, Averback RS, Herr U, Samwer K (1999) Burrowing of Co nanoparticles on clean Cu and Ag surfaces. Phys Rev Lett 83:1163–1166
Acknowledgements
Support for this study from CNPq (Brasil) and CONICYT (Chile), Joint Project CIAM 490891/2008-0 is gratefully acknowledged. We also thank the Millennium Science Nucleus (Chile), Project P10-061-F; Doctorate Program PUC (Chile), Project 06/2009; FONDECYT (Chile), Project 1100365; and CAPES/PROCAD (Brasil) Project 059/2007. Computer time from the National Supercomputing Center CENAPAD CESUP/UFRGS is also acknowledged.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Pérez, M., Muñoz, F., Mejía-López, J. et al. Physical and chemical properties of Co n−m Cu m nanoclusters with n = 2–6 atoms via ab-initio calculations. J Nanopart Res 14, 933 (2012). https://doi.org/10.1007/s11051-012-0933-2
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/s11051-012-0933-2