Spin current distribution in antiferromagnetic zigzag graphene nanoribbons under transverse electric fields

Abstract

The spin current transmission properties of narrow zigzag graphene nanoribbons (zGNRs) have been the focus of much computational research, investigating the potential application of zGNRs in spintronic devices. Doping, fuctionalization, edge modification, and external electric fields have been studied as methods for spin current control, and the performance of zGNRs initialized in both ferromagnetic and antiferromagnetic spin states has been modeled. Recent work has shown that precise fabrication of narrow zGNRs is possible, and has addressed long debated questions on their magnetic order and stability. This work has revived interest in the application of antiferromagnetic zGNR configurations in spintronics. A general ab initio analysis of narrow antiferromagnetic zGNR performance under a combination of bias voltage and transverse electric field loading shows that their current transmission characteristics differ sharply from those of their ferromagnetic counterparts. At relatively modest field strengths, both majority and minority spin currents react strongly to the applied field. Analysis of band gaps and current transmission pathways explains the presence of negative differential resistance effects and the development of spatially periodic electron transport structures in these nanoribbons.

Spin Current Sensing for Selective Detection of Explosive Molecules

“…In this case, the bond current plot features transmitting currents (red arrows) passing through the analyte molecule. The rather heterogeneous or “checkered” response of the TNT current increment signatures shown in Figures and is a consequence of the complex bond current pathways induced by various combinations of bias voltage and transverse electric field loadings, as discussed in ref .…”

“…Double-zeta polarized (DZP) basis sets were used for all atoms, and the mesh cutoff energy was set to 300 Ry. Spin orientations were initialized as antiferromagnetic, that is, oppositely directed along the two free edges of the zGNR. ,, …”

“…Spin orientations were initialized as antiferromagnetic, that is, oppositely directed along the two free edges of the zGNR. 21,22,29 Current transmission through the sensor−analyte combination under the applied electrical loads was computed for 99 different combinations of bias voltage and transverse field: (a) the bias voltage was varied from 0.1 to 1.0 V at an interval of 0.1 V, and (b) the transverse electric field was varied from 0.00 to 0.10 V/Å at an interval of 0.01 V/Å. Bond currents 27 for the system were computed by using an energy-averaging method 29 which provides a global description of electron transmission.…”

“…21,22,29 Current transmission through the sensor−analyte combination under the applied electrical loads was computed for 99 different combinations of bias voltage and transverse field: (a) the bias voltage was varied from 0.1 to 1.0 V at an interval of 0.1 V, and (b) the transverse electric field was varied from 0.00 to 0.10 V/Å at an interval of 0.01 V/Å. Bond currents 27 for the system were computed by using an energy-averaging method 29 which provides a global description of electron transmission. This assists in the interpretation of the modeling results because unlike lumped parameter descriptions of device conductance, aggregate current flow, and so on, it reflects the distributed property characteristics of the system.…”

“…Introducing a sensitivity to the target molecule’s magnetic properties can be expected to improve selectivity; however, as in the case of conventional chemiresistive sensing schemes, multifunctional performance will continue to be desirable, if not essential, in improving overall sensor performance. Basic research on spin current transmission in GNRs has shown that gate voltages, bias voltages, and transverse electric fields may be used to modify current flow in GNRs, , for example by dissimilar adjustment of the spin-up and spin-down band gaps. , More recent research extending these results to narrow “antiferromagnetic” zGNRs under combined bias voltage and transverse electric field loading has established that such loads may offer considerable control in tuning spin current flow in a zGNR sensor. Hence dual-input (bias voltage and electric field) dual-output (total current and spin current difference) zGNR sensors may offer opportunities to identify distinct analyte signatures or “fingerprints” while maintaining the relative simplicity of chemiresistive sensing devices.…”