| We have performed scanning tunnelling spectroscopy measurements on the iron pnictide superconductor LiFeAs in the superconducting state. After cleavage of the crystal, we observe atomically flat surfaces which contain several defects in the field of view (FOV) of about 20nmx20nm. Already in topographic images, pronounced spatial modulations of the integral density of states are present, which are particular strong in the vicinity of the defects. We have perfomed full dI/dV(V) spectroscopy map measurements for determining the energy dependent quasiparticle interference in the FOV. The Fourier transform of the dI/dV maps exhibits a very rich structure which has a strong resemblance of constant energy cuts through the experimental band structure. We discuss the structure in more detail in terms of the experimental band structure, including the van-Hove singularity at the Gamma point. |
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