Gub Gub | IIT Patna (original) (raw)

Papers by Gub Gub

Research on graphene and other two-dimensional atomic crystals is intense and is likely to remain... more Research on graphene and other two-dimensional atomic crystals is intense and is likely to remain one of the leading topics in condensed matter physics and materials science for many years. Looking beyond this field, isolated atomic planes can also be reassembled into designer heterostructures made layer by layer in a precisely chosen sequence. The first, already remarkably complex, such heterostructures (often referred to as 'van der Waals') have recently been fabricated and investigated, revealing unusual properties and new phenomena. Here we review this emerging research area and identify possible future directions. With steady improvement in fabrication techniques and using graphene's springboard, van der Waals heterostructures should develop into a large field of their own. G raphene research has evolved into a vast field with approximately ten thousand papers now being published every year on a wide range of graphene-related topics. Each topic is covered by many reviews. It is probably fair to say that research on 'simple graphene' has already passed its zenith. Indeed, the focus has shifted from studying graphene itself to the use of the material in applications 1 and as a versatile platform for investigation of various phenomena. Nonetheless, the fundamental science of graphene remains far from being exhausted (especially in terms of many-body physics) and, as the quality of graphene devices continues to improve 2-5 , more breakthroughs are expected, although at a slower pace. Because most of the 'low-hanging graphene fruits' have already been harvested, researchers have now started paying more attention to other two-dimensional (2D) atomic crystals 6 such as isolated monolayers and few-layer crystals of hexagonal boron nitride (hBN), molybdenum disulphide (MoS 2), other dichalcogenides and layered oxides. During the first five years of the graphene boom, there appeared only a few experimental papers on 2D crystals other than graphene, whereas the last two years have already seen many reviews (for example, refs 7-11). This research promises to reach the same intensity as that on graphene, especially if the electronic quality of 2D crystals such as MoS 2 (refs 12, 13) can be improved by a factor of ten to a hundred. In parallel with the efforts on graphene-like materials, another research field has recently emerged and has been gaining strength over the past two years. It deals with heterostructures and devices made by stacking different 2D crystals on top of each other. The basic principle is simple: take, for example, a monolayer, put it on top of another mono-layer or few-layer crystal, add another 2D crystal and so on. The resulting stack represents an artificial material assembled in a chosen sequence-as in building with Lego-with blocks defined with one-atomic-plane precision (Fig. 1). Strong covalent bonds provide in-plane stability of 2D crystals, whereas relatively weak, van-der-Waals-like forces are sufficient to keep the stack together. The possibility of making multilayer van der Waals heterostructures has been demonstrated experimentally only

Research on graphene and other two-dimensional atomic crystals is intense and is likely to remain... more Research on graphene and other two-dimensional atomic crystals is intense and is likely to remain one of the leading topics in condensed matter physics and materials science for many years. Looking beyond this field, isolated atomic planes can also be reassembled into designer heterostructures made layer by layer in a precisely chosen sequence. The first, already remarkably complex, such heterostructures (often referred to as 'van der Waals') have recently been fabricated and investigated, revealing unusual properties and new phenomena. Here we review this emerging research area and identify possible future directions. With steady improvement in fabrication techniques and using graphene's springboard, van der Waals heterostructures should develop into a large field of their own. G raphene research has evolved into a vast field with approximately ten thousand papers now being published every year on a wide range of graphene-related topics. Each topic is covered by many reviews. It is probably fair to say that research on 'simple graphene' has already passed its zenith. Indeed, the focus has shifted from studying graphene itself to the use of the material in applications 1 and as a versatile platform for investigation of various phenomena. Nonetheless, the fundamental science of graphene remains far from being exhausted (especially in terms of many-body physics) and, as the quality of graphene devices continues to improve 2-5 , more breakthroughs are expected, although at a slower pace. Because most of the 'low-hanging graphene fruits' have already been harvested, researchers have now started paying more attention to other two-dimensional (2D) atomic crystals 6 such as isolated monolayers and few-layer crystals of hexagonal boron nitride (hBN), molybdenum disulphide (MoS 2), other dichalcogenides and layered oxides. During the first five years of the graphene boom, there appeared only a few experimental papers on 2D crystals other than graphene, whereas the last two years have already seen many reviews (for example, refs 7-11). This research promises to reach the same intensity as that on graphene, especially if the electronic quality of 2D crystals such as MoS 2 (refs 12, 13) can be improved by a factor of ten to a hundred. In parallel with the efforts on graphene-like materials, another research field has recently emerged and has been gaining strength over the past two years. It deals with heterostructures and devices made by stacking different 2D crystals on top of each other. The basic principle is simple: take, for example, a monolayer, put it on top of another mono-layer or few-layer crystal, add another 2D crystal and so on. The resulting stack represents an artificial material assembled in a chosen sequence-as in building with Lego-with blocks defined with one-atomic-plane precision (Fig. 1). Strong covalent bonds provide in-plane stability of 2D crystals, whereas relatively weak, van-der-Waals-like forces are sufficient to keep the stack together. The possibility of making multilayer van der Waals heterostructures has been demonstrated experimentally only