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Author Sevincli, H. ♦ Senger, R. T. ♦ Durgun, E. ♦ Ciraci, S.
Source CiteSeerX
Content type Text
File Format PDF
Subject Domain (in DDC) Computer science, information & general works ♦ Data processing & computer science
Subject Keyword Magnetic Molecule ♦ Oscillatory Exchange Coupling ♦ Carbon Atom ♦ Indirect Exchange Coupling ♦ Exchange Coupling ♦ Molecular Structure ♦ Dft Result ♦ Electronic Version ♦ Antiferromagnetic Configuration ♦ Analogous Extended Structure ♦ Non-magnetic Host Material ♦ Non-magnetic Spacer ♦ Spin-dependent Density Functional Theory ♦ Essential Feature ♦ Tight-binding Model ♦ Band Theory ♦ Oscillatory Exchange ♦ Atomic Magnetic Moment ♦ Magnetic Layer ♦ Quasi-zero-dimensional System ♦ Spin-dependent Onsite ♦ Atomic Picture ♦ Transition Metal ♦ Extended Wavefunctions ♦ Quantum Interference Effect ♦ Tm Cn Tm ♦ Magnetic Impurity ♦ Theoretical Framework ♦ First-principles Calculation ♦ Finite Linear Carbon Chain ♦ Magnetic Ground State ♦ Model Calculation
Abstract Recently, first-principles calculations based on the spin-dependent density functional theory (DFT) have revealed that the magnetic ground state of a finite linear carbon chain capped by two transition metal (TM) atoms alternates between ferromagnetic and antiferromagnetic configurations depending on the number of carbon atoms. The character of indirect exchange coupling in this nanoscale, quasi-zero-dimensional system is different from those analogous extended structures consisting of magnetic layers separated by a non-magnetic spacer (or magnetic impurities in a non-magnetic host material) and a formulation based on an atomic picture is needed. We present a tight-binding model which provides a theoretical framework to the underlying mechanism of the exchange coupling in molecular structures. The model calculations are capable of reproducing the essential features of the DFT results for the indirect exchange coupling and the atomic magnetic moments in the TM–Cn–TM structures as functions of the number of carbon atoms. In nanostructures consisting of a few atoms the concepts of extended wavefunctions and the band theory lose their validity, and hence the oscillatory exchange coupling turns out to be a consequence of quantum interference effects due to the spin-dependent onsite and hopping energies. (Some figures in this article are in colour only in the electronic version) 1.
Educational Role Student ♦ Teacher
Age Range above 22 year
Educational Use Research
Education Level UG and PG ♦ Career/Technical Study
Learning Resource Type Article
Publisher Date 2007-01-01