Quasi freestanding graphene on SiC 0001 via cobalt intercalation of zero layer graphene

Modification of the electronic and crystal structure of zero layer graphene grown on 6H SiC 0001 after Co intercalation is reported. Using a wide range of techniques including angle resolved photoelectron spectroscopy, x ray photoelectron spectroscopy, Raman spectroscopy, low energy electron diffraction, we found that zero layer graphene on SiC transforms into graphene monolayer as a result of cobalt intercalation. The Dirac cone of amp; 960; band characteristic of quasi freestanding graphene is observed. In combination with high resolution transmission electron microscopy and atomic force microscopy data, we conclude that ultrathin silicide CoSi CoSi2 structure is formed between graphene and SiC substrate. Investigation of magnetic properties reveals ferromagnetic behavior with open hysteresis loop. The results of this work are the basis for further implementation of magneto spin orbit graphene on a semiconducting substrate and are important for the future application of such graphene in spintronic

Non monotonic variation of the Kramers point band gap with increasing magnetic doping in BiTeI

Polar Rashba type semiconductor BiTeI doped with magnetic elements constitutes one of the most promising platforms for the future development of spintronics and quantum computing thanks to the combination of strong spin orbit coupling and internal ferromagnetic ordering. The latter originates from magnetic impurities and is able to open an energy gap at the Kramers point KP gap of the Rashba bands. In the current work using angle resolved photoemission spectroscopy ARPES we show that the KP gap depends non monotonically on the doping level in case of V doped BiTeI. We observe that the gap increases with V concentration until it reaches 3 and then starts to mitigate. Moreover, we find that the saturation magnetisation of samples under applied magnetic field studied by superconducting quantum interference device SQUID magnetometer has a similar behaviour with the doping level. Theoretical analysis shows that the non monotonic behavior can be explained by the increase of antiferromagnetic coupled atoms of magnetic impurity above a certain doping level. This leads to the reduction of the total magnetic moment in the domains and thus to the mitigation of the KP gap as observed in the experiment. These findings provide further insight in the creation of internal magnetic ordering and consequent KP gap opening in magnetically doped Rashba type semiconductor