Creating, moving and merging Dirac points with a Fermi gas in a tunable honeycomb lattice

Details Creating, moving and merging Dirac points with a Fermi gas in a tunable honeycomb lattice Creating, moving and merging Dirac points with a Fermi gas in a tunable honeycomb lattice

2011-11-21

arxiv.org/abs/1111.5020v1

Physics

Condensed Matter

Quantum Gases

Scientific paper

Dirac points lie at the heart of many fascinating phenomena in condensed matter physics, from massless electrons in graphene to the emergence of conducting edge states in topological insulators [1, 2]. At a Dirac point, two energy bands intersect linearly and the particles behave as relativistic Dirac fermions. In solids, the rigid structure of the material sets the mass and velocity of the particles, as well as their interactions. A different, highly flexible approach is to create model systems using fermionic atoms trapped in the periodic potential of interfering laser beams, a method which so far has only been applied to explore simple lattice structures [3, 4]. Here we report on the creation of Dirac points with adjustable properties in a tunable honeycomb optical lattice. Using momentum-resolved interband transitions, we observe a minimum band gap inside the Brillouin zone at the position of the Dirac points. We exploit the unique tunability of our lattice potential to adjust the effective mass of the Dirac fermions by breaking inversion symmetry. Moreover, changing the lattice anisotropy allows us to move the position of the Dirac points inside the Brillouin zone. When increasing the anisotropy beyond a critical limit, the two Dirac points merge and annihilate each other - a situation which has recently attracted considerable theoretical interest [5{9], but seems extremely challenging to observe in solids [10]. We map out this topological transition in lattice parameter space and find excellent agreement with ab initio calculations. Our results not only pave the way to model materials where the topology of the band structure plays a crucial role, but also provide an avenue to explore many-body phases resulting from the interplay of complex lattice geometries with interactions [11, 12].

Affiliated with

Also associated with

No associations

Rating

Creating, moving and merging Dirac points with a Fermi gas in a tunable honeycomb lattice does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Creating, moving and merging Dirac points with a Fermi gas in a tunable honeycomb lattice, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Creating, moving and merging Dirac points with a Fermi gas in a tunable honeycomb lattice will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-551356