Light-induced irreversible structural phase transition in trilayer graphene

A crystal structure has a profound influence on the physical properties of the corresponding material. By synthesizing crystals with particular symmetries, one can strongly tune their properties, even for the same chemical configuration (compare graphite and diamond, for instance). Even more interesting opportunities arise when the structural phases of crystals can be changed dynamically through external stimulations. Such abilities, though rare, lead to a number of exciting phenomena, such as phase-change memory effects. In the case of trilayer graphene, there are two common stacking configurations (ABA and ABC) that have distinct electronic band structures and exhibit very different behaviors. Domain walls exist in the trilayer graphene with both stacking orders, showing fascinating new physics such as the quantum valley Hall effect. Extensive efforts have been dedicated to the phase engineering of trilayer graphene. However, the manipulation of domain walls to achieve precise control of local structures and properties remains a considerable challenge. Here, we experimentally demonstrate that we can switch from one structural phase to another by laser irradiation, creating domains of different shapes in trilayer graphene. The ability to control the position and orientation of the domain walls leads to fine control of the local structural phases and properties of graphene, offering a simple but effective approach to create artificial two-dimensional materials with designed atomic structures and electronic and optical properties.
Laser on trilayer graphene: stack switch with a difference Heat from a laser changes how atoms stack up within trilayer graphene, providing a simple and effective approach for fabricating new materials with interesting optical and electronic properties. Mengjian Zhu of China’s National University of Defense Technology and colleagues used laser light to switch regions within trilayer graphene from one type of atomic layering to another. This is interesting, as the properties of trilayer graphene vary depending on how its atoms are stacked up. Zhu and his colleagues found that heat from the laser manipulated the dividing walls separating differently stacked atomic regions within the graphene flakes. This led to a gradual switch from one type of atomic stacking to another, changing the graphene’s properties. The finding could lead to applications for optical storage media and photonic devices.