Quasi-Ferromagnet Spintronics in Graphene Nanodisk-Lead System
arXiv:0910.0593 · doi:10.1088/1367-2630/11/9/095005
Abstract
A zigzag graphene nanodisk can be interpreted as a quantum dot with an internal degree of freedom. It is well described by the infinite-range Heisenberg model. We have investigated its thermodynamical properties. There exists a quasi-phase transition between the quasi-ferromagnet and quasi-paramagnet states, as signaled by a sharp peak in the specific heat and in the susceptability. We have also analyzed how thermodynamical properties are affected when two leads are attached to the nanodisk. It is shown that lead effects are described by the many-spin Kondo Hamiltonian. There appears a new peak in the specific heat, and the multiplicity of the ground state becomes just one half of the system without leads. Another lead effect is to enhance the ferromagnetic order. Being a ferromagnet, a nanodisk can be used as a spin filter. Furthermore, since the relaxation time is finite, it is possible to control the spin of the nanodisk by an external spin current. We then propose a rich variety of spintronic devices made of nanodisks and leads, such as spin memory, spin amplifier, spin valve, spin-field-effect transistor, spin diode and spin logic gates such as spin-XNOR gate and spin-XOR gate. Graphene nanodisks could well be basic components of future nanoelectronic and spintronic devices.
12 pages, 13 figures, invited paper to "focus on graphene"
References in corpus (17)
- Electric Field Effect in Atomically Thin Carbon Films
- Two-Dimensional Gas of Massless Dirac Fermions in Graphene
- Experimental Observation of Quantum Hall Effect and Berry's Phase in Graphene
- Spintronics: Fundamentals and applications
- Energy Band Gap Engineering of Graphene Nanoribbons
- Energy Gaps in Graphene Nanoribbons
- Electron transport through double quantum dots
- Electronic States of Graphene Nanoribbons
- Magnetism in graphene nano-islands
- Peculiar Width Dependence of the Electronic Property of Carbon Nanoribbons
- Metallic Graphene Nanodisks
- Half-metallic graphene nanodots
- Topological Frustration in Graphene Nanoflakes: Magnetic Order and Spin Logic Devices
- Coherent transport in graphene nanoconstrictions
- Graphene Nanoribbon and Graphene Nanodisk
- Coulomb Blockade in Graphene Nanodisks
- Spin Filter, Spin Amplifier and Other Spintronic Applications in Graphene Nanodisks
Cited by in corpus (6)
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- Generation and Manipulation of Spin Current in Graphene Nanodisks: Robustness against Randomness and Lattice Defects
- Electric field control of the indirect magnetic coupling through a short graphene nanoribbon
- Ground-state magnetic phase diagram of bow-tie graphene nanoflakes in external magnetic field
- Study of decoherence in models for hard-core bosons coupled to optical phonons