Substrate-assisted asymmetric electronic gap in artificial magnetic honeycomb lattice

An artificial magnetic honeycomb lattice was prepared via physical vapor deposition. Asymmetric electronic gaps with increasing broadness were observed in the differential conductivity when applying in-plane current at low temperatures ranging from 27K to 40 K. Electrical hysteresis behavior was also observed and became more profound with increasing temperature. It was seen that an in-plane magnetic field parallel or antiparallel to the applied current tends to narrow the aforementioned gaps and reduce the degree of asymmetry drastically. Resistance measurement with applied magnetic field up to 8.5 T shows a temperature-dependent transition from positive magnetoresistance to negative magnetoresistance, which we suspect, is subject to the effect of the substrate. The observed negative magnetoresistance can be explained as the giant magnetoresistance effect due to the ordering of magnetic moment on the artificial honeycomb lattice.