Giant magnetoresistance and spin Seebeck coefficient in zigzag α-graphyne nanoribbons

Abstract

We investigate the spin-dependent electric and thermoelectric properties of ferromagnetic zigzag α-graphyne nanoribbons (ZαGNRs) using density-functional theory combined with non-equilibrium Green's function method. A giant magnetoresistance is obtained in the pristine even-width ZαGNRs and can be as high as 10(6)%. However, for the doped systems, a large magnetoresistance behavior may appear in the odd-width ZαGNRs rather than the even-width ones. This suggests that the magnetoresistance can be manipulated in a wide range by the dopants on the edges of ZαGNRs. Another interesting phenomenon is that in the B- and N-doped even-width ZαGNRs the spin Seebeck coefficient is always larger than the charge Seebeck coefficient, and a pure-spin-current thermospin device can be achieved at specific temperatures.

Atomistic switch of giant magnetoresistance and spin thermopower in graphene-like nanoribbons

“…1(f,g). The corresponding magnetoresistance R M is about 100% for even n and very small for odd n 1011121317. In the presence of U i , we will present the results for U i  > 0 in two typical cases, i  = 0 and i  > 0 in the following since those for U i  < 0 or i  < 0 can be then deduced based on the symmetry of the systems.…”

“…The GMR and thermopower effects are both intrinsically relevant to the transmission spectrum in tunneling junctions. Recently, magnetoresistance78910111213 and spin thermopower13141516 in graphene-like nanoribbons have become one of the focuses.…”

Spin-dependent Seebeck effects in graphene-based molecular junctions

“…Some investigations indicated that spin thermopower and figure of merit can be largely increased by cutting graphene to be specific configurations, such as sawtooth [22], nanowiggles [23], and rectangular rings [24]. Spin-dependent Seebeck effects have also been detected in other hexagonal honeycomb structures, such as α-ZGNRs [25] and silicene nanoribbons [26]. Although many investigations have been carried out to investigate spin-dependent Seebeck effects in ZGNRs, few investigations were focused on spin thermoelectric transport properties in graphene-based magnetic molecular junctions.…”

Thermoelectric properties of graphene-like nanoribbon studied from the perspective of symmetry

“…External magnetic field can drive a ZNR in its AFM insulator state into its FM metallic state. In this case, charge and spin thermoelectric properties of 1D graphene-like ZNRs have attracted intensive attention in the past decade 4,6,[19][20][21][22][23][24][25][26][27][28] .…”

“…However, the Seebeck coefficients are usually low in perfect intrinsic ZNRs because the slope of transmission spectra vanishes for both spins near the Fermi level. Breaking the geometry symmetry of ZNRs may modulate the energy dependence of transmission 4,19,29,30 and enhance the Seebeck coefficients 4,5,23,31 . Furthermore, edge disorder may enhance the thermoelectric ZT by reducing dramatically phonon thermal transport but affecting only weakly the electronic conduction 23 .…”