Gate-Tunable Large Negative Tunnel Magnetoresistance in Ni–C₆₀–Ni Single Molecule Transistors

Abstract

We have fabricated single C(60) molecule transistors with ferromagnetic Ni leads (FM-SMTs) by using an electrical break junction method and investigated their magnetotransport. The FM-SMTs exhibited clear gate-dependent hysteretic tunnel magnetoresistance (TMR) and the TMR values reached as high as -80%. The polarity of the TMR was found to be always negative over the entire bias range studied here. Density functional theory calculations show that hybridization between the Ni substrate states and the C(60) molecular orbitals generates an antiferromagnetic configuration in the local density of states near the Fermi level, which gives a reasonable explanation for the observed negative TMR.

Electrode Design for Antiparallel Magnetization Alignment in Nanogap Devices

“…1 was designed with 20 nm thickness, and length scales that approximated the dimensions used in Refs. [16][17][18]. Results of the simu- lations with this model validate that it will not accurately produce a uniform AP configuration between source and drain contacts.…”

“…Earlier experimental efforts to create magnetic nanocontact devices that could be alternated between P and AP configurations focused on shape anisotropy, utilizing two electrodes with different shapes, [16][17][18] like the triangle-rectangle (T-R) geometry in Fig. 1, connected via atomic-scale contacts or tunneling gaps formed with standard break junction techniques.…”

Controlled electrode magnetization alignment in planar elliptical ferromagnetic break junction devices

“…P) to non-collinear configurations, [5][6][7] or to a local AP configuration through the creation of neighboring vortex states [8][9][10]. However, the homogeneous (monodomain) AP configuration, required for eliminating the inter-electrode field and ensuring maximum spin polarization, has proven difficult to achieve.…”

Designing cross-linked carbon nanotubes as perfect spin filter and spin valve

“…So far, many kinds of molecular materials have been chosen to construct the spintronic devices, such as carbon nanotubes (CNTs) [9][10][11][12], C 60 [13,14], graphene nanoribbons [15][16][17][18], zigzag a-graphyne nanoribbons [19], boron nitride nanoribbons [20], n-acenes family [21], etc. Especially, CNTs have greatly stimulated the interest of researchers due to their long phase-coherence and spin scattering lengths.…”