Mar 28, 2014
Tweaking the magnetism of molybdenum sulphide nanoribbons
The scaling of field-effect transistors as well as conventional charge-based computer systems is reaching fundamental limits. So there is a call for alternative device concepts. One among the few available approaches is to stick with the original concepts and introduce new materials. In Nanotechnology 25 165703 we use first principle calculations to study MoS2 nanoribbons and show how edge passivating with H and C can be used to tune the magnetism for devices.
The net charge accumulation in H-zz-MoS2-nR compared with zz-MoS2-nR and that of H-zz-MoS2-nR-H compared with zz-MoS2-nR.
Molybdenum sulphide as a competitor to silicon and graphene
MoS2 belongs to the family of layered transition metal dichalcogenides, which are particularly interesting in the field of nanoelectronics and optoelectronics. While graphene sheets are expected to be scalable beyond the current limits of conventional charge-based computer systems, MoS2 with a large band gap and with high mechanical stability, stands out as a serious alternative competitor to graphene for replacing silicon in next-generation field effect transistors.
The successful fabrication of atomic layers of MoS2 in the form of nanosheets, nanotubes and even thin films has further triggered research interest in their rich electronic and magnetic properties. With tuned magnetism, two-dimensional MoS2 structures are expected to open up further possible applications in next-generation spintronics devices.
Edge-dependent properties in MoS2 nanoribbons
We find a significant tweak in the edge-dependent electronic and magnetic properties of MoS2 nanoribbons when the ribbon edges are passivated with hydrogen and carbon atoms in different ways. Our first-principles calculations predict that zig-zag type ribbons of different widths will be metallic and ferromagnetic.
Furthermore, with one edge H passivated, the net magnetic moment of the ribbon increases. In contrast with both edges H passivated, the magnetic moment rather decreases when compared with the pristine ribbon. Interestingly, with C passivation the trend in the magnetic moment changes is the reverse. These different trends in the change in magnetic moment are attributed to the hybridization between Mo and the passivating elements H and C.
Nanoribbons modeled with an armchair type of edge are found to be non-magnetic and semiconducting. We find that the band gap of arm-chair-type nanoribbons increases when both sides are passivated with H and C compared with when just one side is passivated.
The results may have applications in the development of alternative computing systems and next-generation spintronics. We are now planning to contact experimental groups to synthesize these materials.
More information about the research can be found in the journal Nanotechnology 25 165703.
About the author
Puspamitra Panigrahi is a postdoctoral researcher at the Condensed Matter Theory Group at Uppsala University in Sweden. Myskal Sagynbaeva and Muhammad Ramzan, are both also at Uppsala University, and Yunguo Li is at the Royal Institute of Technology. Myskal Sagynbaeva is also affiliated with the Talas State University. The supervisor of this research is Professor Rajeev Ahuja.