Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session J50: Straintronics: Tuning the electronic properties of 2D materials by strain engineeringInvited Live
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Sponsoring Units: DCMP Chair: Eric Hudson, Pennsylvania State University |
Tuesday, March 16, 2021 3:00PM - 3:36PM Live |
J50.00001: Room temperature strain-induced Landau levels in graphene on a wafer-scale platform Invited Speaker: Andrea Damascelli Graphene is a powerful playground for studying a plethora of quantum phenomena. One of the remarkable properties of graphene arises when it is strained in particular geometries and the electrons behave as if they were under the influence of a magnetic field. Previously, these strain-induced pseudomagnetic fields have been explored on the nano- and micrometer-scale using scanning probe and transport measurements. Heteroepitaxial strain, in contrast, is a wafer-scale engineering method. Here, we show that pseudomagnetic fields can be generated in graphene through wafer-scale epitaxial growth. Shallow triangular nanoprisms in the SiC substrate generate strain-induced uniform fields of 41 T, enabling the observation of strain-induced Landau levels at room temperature, as detected by angle-resolved photoemission spectroscopy, and confirmed by model calculations and scanning tunneling microscopy measurements. Our work demonstrates the feasibility of exploiting strain-induced quantum phases in two-dimensional Dirac materials on a wafer-scale platform, opening the field to new applications [1]. |
Tuesday, March 16, 2021 3:36PM - 4:12PM Live |
J50.00002: Evidence of flat bands and correlated states in buckled graphene superlattices Invited Speaker: Jinhai Mao Two-dimensional atomic crystals can radically change their properties in response to external influences, such as substrate orientation or strain, forming materials with novel electronic structure. An example is the creation of weakly dispersive, ‘flat’ |
Tuesday, March 16, 2021 4:12PM - 4:48PM Live |
J50.00003: Building crystals from moiré interfaces Invited Speaker: Stephen Carr When similar 2D materials are stacked on top of one another with slight misalignment, a moiré pattern creates periodic variations in the interlayer electronic coupling. The variations can localize electronic states, promoting non-linear effects and strongly correlated phases. In this talk the microscopic origins of electronic moiré potentials will be examined alongside the wide ranging possibilities for the electronic states they produce. This includes expanding beyond two layer systems, combining multiple distinct materials, and tuning the electronic and atomic structure of moire interfaces with external perturbations. Controlling moiré patterns with strain engineering emerges as a vital step in the development of these artificial crystals, which are already probing long-standing questions in condensed matter physics and could serve as ideal platforms for quantum or topological electronics. |
Tuesday, March 16, 2021 4:48PM - 5:24PM Live |
J50.00004: Band flattening in periodically buckled monolayer graphene Invited Speaker: Francois Peeters The strain fields induced by periodically buckling graphene result in a periodic pseudo-magnetic field that modifies the electronic band structure. From the geometry, amplitude, and period of the periodic pseudo-magnetic field, we determine the necessary conditions to access the regime of correlated phases by examining the band flattening. As compared to twisted bilayer graphene the proposed system has the advantages that: 1) only a single layer of graphene is needed, 2) one is not limited to hexagonal superlattices, and 3) narrower flat bandwidth and larger separation between flat bands can be induced. Periodically strained monolayer of graphene can become a platform for the exploration of exotic many-body phases. |
Tuesday, March 16, 2021 5:24PM - 6:00PM Live |
J50.00005: Strain Modulated Superlattices in Graphene Invited Speaker: Eric Hudson The quest to create novel material systems with designer electronic properties has often led to the investigation of interfaces and superlattices. The potential of customizing properties by merging different 2D materials via vertical or horizontal stacking to create van der Waals or lateral heterostructures seems limitless. In this presentation I will discuss an alternative approach. The local electronic properties of a continuous graphene sheet can be periodically varied by strain modulation, created by exerting extreme (>10%) shear and tensile strains. Similar to a sheet of plastic wrap pulled taut at its edges, the graphene buckles, forming nanoscale ripples. Within these strain-induced ripples the carbon-carbon bond lengths vary from short to long, creating dense and rare regions of the material respectively, with properties as different as in two different materials. Thus a single graphene sheet effectively becomes an electronic superlattice in which novel electronic states arise at the interfaces. I will present the results of scanning tunneling microscopy and theoretical investigations of this system, and discuss their potential to help realize many longstanding theoretical proposals, such as valley filters, snake states and electron optics in graphene and other 2D materials |
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