Experimental realization and characterization of an electronic Lieb lattice

ROM 2017-07
Author: M. R. Slot / M.R.Slot@uu.nl
Institute: 1. Debye Institute for Nanomaterials Science, Utrecht University, the Netherlands 2. Institute for Theoretical Physics, Utrecht University, the Netherlands
Publication: M.R. Slot, T.S. Gardenier, P.H. Jacobse, G.C.P. van Miert, S.N. Kempkes, S.J.M. Zevenhuizen, C. Morais Smith, D. Vanmaekelbergh and I. Swart, Experimental realization and characterization of an electronic Lieb lattice, Nature Physics http://dx.doi.org/10.
Instrument: LT STM

Novel two-dimensional materials with promising electronic band structures can be engineered by tailoring their lattice geometries. The honeycomb lattice of graphene, for instance, gives rise to Dirac cones in which charge carriers behave as effectively massless particles. The square-depleted geometry of a Lieb lattice (shown in Fig. 1a) also gives rise to linearly dispersing bands, similar to graphene, with a flat band intersecting the Dirac cones (see Fig. 1c). Whereas optical and photonic Lieb lattices have been studied experimentally [1], an electronic Lieb lattice had not been realized so far.

M.R. Slot et al., Nat. Phys. http://dx.doi.org/10.1038/nphys4105 (2017) reports on the realization of an electronic Lieb lattice using a strategy similar to the method employed for creating artificial graphene [2]: carbon monoxide molecules on Cu(111) are positioned into an anti-lattice by lateral manipulation using an STM tip, confining the copper surface state electrons into the desired lattice (cf. Fig. 1a-c). The characteristic electronic structure of the Lieb lattice, as simulated using a muffin-tin and tight-binding approach, was confirmed by scanning tunneling spectroscopy and wavefunction mapping (see Fig. 2). Moreover, second-order electronic patterns were observed at higher energies. The Cu(111)/CO system forms a versatile model system, which allows one to study novel lattice geometries and to tune parameters that cannot be accessed in real solid-state materials. The scanning tunnelling microscope facilitates the realization as well as the structural and electronic characterization of the lattice, paving the way for the design of truly novel two-dimensional materials.

Marlou R. Slot1, Thomas S. Gardenier1, Peter H. Jacobse1, Guido C. P. van Miert2, Sander N. Kempkes2, Stephan J. M. Zevenhuizen1, Cristiane Morais Smith2, Daniel Vanmaekelbergh1 & Ingmar Swart1