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

Abstract

We demonstrate that the giant magnetoresistance can be switched off (on) in even- (odd-) width zigzag graphene-like nanoribbons by an atomistic gate potential or edge disorder inside the domain wall in the antiparallel (ap) magnetic configuration. A strong magneto-thermopower effect is also predicted that the spin thermopower can be greatly enhanced in the ap configuration while the charge thermopower remains low. The results extracted from the tight-binding model agree well with those obtained by first-principles simulations for edge doped graphene nanoribbons. Analytical expressions in the simplest case are obtained to facilitate qualitative analyses in general contexts.

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

“…In the existence of disorders, transmission dips may appear due to the Fano effect arising from the formation of impurity bound states. Theses characteristic transmission dips have been confirmed by DFT simulations in FM nanoribbons of graphene-like-materials 4,19,20,45,46 . In addition, the disorders in the central region can break the geometric symmetry of the system and couple the orthogonal wave functions between the electrodes in case ap.…”

“…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] .…”

“…This allows continuous variation of disorder parameters and facilitates systematic investigation on the effects of disorder configuration and profile. In a previous work, using a tight-binding model for FM ZNRs, we have studied effects of local potential at a single site on the charge and spin thermopower and obtained inspiring result 20 . Comparison with the first-principles calculation of edge doped ZGNRs shows that boron atom doping corresponds to add an external on-site potential of 3.24 eV.…”

“…In systems with disorders such as dopants, defects, and applied gate voltages, the profile of on-site energies α α U k describes their effects. It has been shown that an edge dopant of single boron atom in ZGNRs gives a U around 3 eV 20 .…”

Electronic Structure and I-V Characteristics of InSe Nanoribbons

“…One-dimensional (1D) nanoribbons can then be fabricated by tailoring the 2D materials [ 5 ] or assembling atoms precisely in the bottom-up way [ 6 , 7 ]. In the nanoribbons, the electronic properties are further modulated by additional confinement and possible edge functionalization [ 8 , 9 ]. For example, their energy gap, a key parameter of semiconductor, may be continuously adjusted by their width [ 10 – 15 ].…”