Mukul Kabir

Structure, bonding, and magnetism of cobalt clusters from first-principles calculations

S. Datta, M. Kabir, S. Ganguly, B. Sanyal, T. Saha-Dasgupta, and A. Mookerjee Department of Material Sciences, S.N. Bose National Centre for Basic Sciences, JD Block, Sector-III, Salt Lake City, Kolkata 700 098, India Theoretical Magnetism Group, Department of Physics, Uppsala University, Box 530, SE-75121 Uppsala, Sweden Unit for Nanoscience and Technology, S.N. Bose National Centre for Basic Sciences, JD Block, Sector-III, Salt Lake City, Kolkata 700 098, India (Dated: February 1, 2008)

Structure, electronic properties, and magnetic transition in manganese clusters

We systematically investigate the structural, electronic, and magnetic properties of Mnn clusters n =2–2 0 within the ab initio pseudopotential plane wave method using generalized gradient approximation for the exchange-correlation energy. A new kind of icosahedral structural growth has been predicted in the intermediate size range. Calculated magnetic moments show an excellent agreement with the Stern-Gerlach experiment. A transition from ferromagnetic to ferrimagnetic Mn-Mn coupling takes place at n = 5 and the ferrimagnetic states continue to be the ground states for the entire size range. Possible presence of multiple isomers in the experimental beam has been argued. No signature of nonmetal to metal transition is observed in this size range and the coordination dependence of d-electron localization is discussed.

Magnetism in small bimetallic Mn-Co clusters

Effects of alloying on the electronic and magnetic properties of MnxCoy (x+y=n=2-5, x=0-n) and Mn2Co11 nanoalloy clusters are investigated using the density-functional theory. Unlike the bulk alloy ...

First-principles study of structural stability and electronic structure of CdS nanoclusters

Using first-principles density functional calculations, we have studied the structural stability of stoichiometric as well as nonstoichiometric CdS nanoclusters at ambient pressure with diameters ranging up to about 2.5 nm. Our study reveals that the relative stability of the two available structures for CdS, namely zincblende and wurtzite, depends sensitively on the details like surface geometry and/or surface chemistry. The associated band gap also exhibits nonmonotonic behavior as a function of cluster size. Our findings may shed light on reports of experimentally observed structures and associated electronic structures of CdS nanoclusters found in the literature.

Emergence of noncollinear magnetic ordering in small magnetic clusters: Mn n and As@Mn n

Using first-principles density functional calculations, we have studied the magnetic ordering in pure Mn n (n=2-10,13,15,19) and As@Mn n (n=1-10) clusters. Although, for both pure and doped manganese clusters, there exists many collinear and noncollinear isomers close in energy, the smaller clusters with n≤5 have collinear magnetic ground states and the emergence of noncollinear ground states is seen for n≥6 clusters. Due to strong p-d hybridization in As@Mn n clusters, the binding energy is substantially enhanced and the magnetic moment is reduced compared to the corresponding pure Mn n clusters.

A real-space study of random extended defects in solids : Application to disordered Stone–Wales defects in graphene

Abstract We propose here a first-principles, parameter free, real space method for the study of disordered extended defects in solids. We shall illustrate the power of the technique with an application to graphene sheets with randomly placed Stone–Wales defects and shall examine the signature of such random defects on the density of states as a function of their concentration. The technique is general enough to be applied to a whole class of systems with lattice translational symmetry broken not only locally but by extended defects and defect clusters. The real space approach will allow us to distinguish signatures of specific defects and defect clusters.

Ab initio study of structural stability of small 3d late transition metal clusters: interplay of magnetization and hybridization

Using first-principles density functional theory based calculations, we analyze the structural stability of small clusters of 3

Transition Metal and Vacancy Defect Complexes in Phosphorene: A Spintronic Perspective

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Kinetics of Topological Stone–Wales Defect Formation in Single-Walled Carbon Nanotubes

late transition metals. We consider the relative stability of the two structures - layer-like structure with hexagonal closed packed stacking and more compact structure of icosahedral symmetry. We find that the Co clusters show an unusual stability in hexagonal symmetry compared to the small clusters of other members which are found to stabilize in icosahedral symmetry based structure. Our study reveals that this is driven by the interplay between the magnetic energy gain and the gain in covalency through

Manipulation of edge magnetism in hexagonal graphene nanoflakes

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