A Theoretical Study on SpinDependent Transport of FerromagnetCarbon Nanotube Encapsulating.pdfVIP

A Theoretical Study on Spin-Dependent Transport of “Ferromagnet/Carbon Nanotube Encapsulating Magnetic 4 Atoms/Ferromagnet” Junctions with 4-Valued Conductances 0 0 2 Satoshi Kokado1,2 ∗ and Kikuo Harigaya2,3 † l u 1Faculty of Engineering, Shizuoka University, Hamamatsu 432-8561, Japan J 2Nanotechnology Research Institute, AIST, Tsukuba 305-8568, Japan 6 1 3 Synthetic Nano-Function Materials Project, AIST, Tsukuba 305-8568, Japan ] (February 2, 2008) l l a h s- Abstract e m t. As a novel function of ferromagnet (FM)/spacer/FM junctions, we theoreti- a m cally investigate multiple-valued (or multi-level) cell property, which is in prin- - ciple realized by sensing conductances of four states recorded with magnetiza- d tion configurations of two FMs; (up,up), (up,down), (down,up), (down,down). n o In order to sense all the states, 4-valued conductances corresponding to the c respective states are necessary. We previously proposed that 4-valued con- [ ductances are obtained in FM1/spin-polarized spacer (SPS)/FM2 junctions, 1 v where FM1 and FM2 have different spin polarizations, and the spacer de- 9 pends on spin [J. Phys.: Condens. Matter 15, 8797 (2003)]. In this paper, an 3 4 ideal SPS is considered as a single-wall armchair carbon nanotube encapsulat- 7 ing magnetic atoms, where the nanotube shows on-resonance or off-resonance 0 at the Fermi level according to its length. The magnitude of the obtained 4- 4 0 valued conductances has an opposite order between the on-resonant