To find the magnetic ground state configuration, we first optimized the unit cell of both 13ZGNRH and 12AGNRH in non-magnetic (NM), anti-ferromagnetic (AFM) and ferromagnetic (FM) state, wherein the computed energy difference and magnetic moments are tabulated in Table . For 13AGNRH, the negligible energy difference i. ). The isosurface plot of spin-polarized density for 12ZGNRH in AFM state shown in Figure , also agrees with the reported finding that local magnetization is staggered on edge C-atoms, with ferromagnetic ordering within the edge and anti-ferromagentic coupling between both the edges. This indicates that the dominant peaks near Fermi energy in ZGNRH arises from edge C-atoms which contains the unpaired electrons with opposite spin orientation. It is further worthy to point that although 12ZGNRH possess AFM ground state with spin-polarized edge C-atoms, however both band structure and DOS plot reveals spin degenerate levels in AFM state, similar to that of NM AGNRH. In nutshell, the most salient difference between AGNRH and ZGNRH is the existence of antiferromagnetically coupled localized edge states, found exclusively for ZGNRH. Thus, one can infer that AFM ground state in ZGNR might play a significant role in mediating spin-polarized transmission through ZGNR, however the spin-degenerate levels limit its applications in AFM ground state. With this understanding, here we probed the plausibility of exploiting the low-lying FM state of ZGNRH to successfully trigger the spin-polarization effects. As illustrated in Figure , the band structures and DOS plots for ZGNRH are first examined in all the states, i.e., NM, AFM and FM state. The band structure reveals that in NM state (Figure ), band become degenerate exactly at Fermi energy. This leads to high density of states with a sharp peak at Fermi level, suggesting instability in the electronic structure. Further, the peak at E f in NM state also points towards the metallic nature of ZGNRH is NM state.