Dispersing artifacts in FT-STS: a comparison of set point effects across acquisition modes

Abstract

Abstract. Fourier transform scanning tunnelling spectroscopy (FT-STS), or quasiparticle interference (QPI), has become an influential tool for the study of a wide range of important materials in condensed matter physics. However, FT-STS in complex materials is often challenging to interpret, requiring significant theoretical input in many cases, making it crucial to understand potential artifacts of the measurement. Here, we compare the most common modes of acquiring FT-STS data and show through both experiment and simulations that artifact features can arise that depend on how the tip height is stabilized throughout the course of the measurement. The most dramatic effect occurs when a series of dI/dV maps at different energies are acquired with simultaneous constant current feedback; here a feature that disperses in energy appears that is not observed in other measurement modes. Such artifact features are similar to those arising from real physical processes in the sample and are susceptible to misinterpretation.

Observation of Effective Pseudospin Scattering in ZrSiS

“…We observe two separate branches with a negative slope above E F at a large positive energy, and a strong nondispersive feature, accompanied by a weaker dispersive feature, below E F (red arrows). The same nondispersing qvector in the valence was observed in data obtained by both constant current and constant height mode measurements, excluding the set point effect 26 as a possible cause. Both the second negative-slope feature above E F and the nondispersive feature below E F are not present in our T-matrix calculation (Figure 3b) but are reproduced well in the JDOS calculation (Figure 3c); both features result from pseudospin nonconserving processes at Q 2 .…”

Algorithm for subcycle terahertz scanning tunneling spectroscopy

“…In addition to ρ sample , conventional STM can also resolve surface band structure through quasiparticle interference (QPI) imaging [36,40]. Differential conductance images are recorded near a defect or step edge, showing oscillatory (interference) features.…”

Direct comparison of ARPES, STM, and quantum oscillation data for band structure determination in Sr2RhO4

“…1d. To mitigate the set-up effect, we take the Fourier transform not of the conductance layers dI/dV(r,eV), but of the normalized conductance data, dI/dV(r,eV)/(I(r,eV)/V), where I(r,eV) is the tunnelling current and V is the bias voltage (see discussion in the methods and Supplementary Figure 11) [28][29][30][31][32] . For the β band, we directly observe the STM 'Fermi surface' with wave-vector q=2kF.…”

“…(𝑒𝑉, 𝐫) = . The procedure can thus introduce additional artifacts into the measured differential conductance 𝑑𝐼/𝑑𝑉 28,55 , the socalled set-up effect.…”