Electronic and magnetic properties of bulk Cr tips for scanning tunneling spectroscopy

Abstract

The electronic and magnetic properties of bulk Cr tips for scanning tunneling microscopy have been investigated by means of density functional theory (DFT) calculations and scanning tunneling spectroscopy (STS) measurements. Spin-resolved densities of states (DOS) were calculated for model tips, i.e., Cr adatoms and clusters on ideal Cr surfaces. STS measurements on Au(111) and Si(111)-7×7 have been interpreted by modeling the tunneling process in a Wentzel-Kramers-Brillouin approximation in order to ascertain the role of tip DOS features. Calculated spin-resolved electronic properties of Cr tips have been used to revisit spin-polarized (SP) STS measurements from the literature. The agreement between experimental findings and DFT calculations confirms the relevance of the knowledge of tip electronic properties and of an appropriate model for the tunneling process in the interpretation of STS and SP-STS data.

The impact of structural relaxation on spin polarization and magnetization reversal of individual nano structures studied by spin-polarized scanning tunneling microscopy

“…Maps of the asymmetry, calculated from the corresponding differential conductance, are analyzed in the next section to characterize the spatial dependence of the spin-polarization. The asymmetry signal shows a pronounced energy dependence [47,67,68]. We compared the energy dependence of the experimental asymmetry with that of the calculated spin-polarization (see supplementary online material of reference [15]).…”

Arbitrary tip orientation in STM simulations: 3D WKB theory and application to W(110)

“…The difference between model magnetic tips on the spin-polarized spectroscopic properties (SP-STS) was investigated in Refs. [19,20]. Magnetic contrast variations were studied in spin-polarized STM (SP-STM) on a noncollinear magnetic surface in Refs.…”

Note: Fabrication and characterization of molybdenum tips for scanning tunneling microscopy and spectroscopy

“…11 Of course, Mo tips may present different possible electronic configurations of the tip apex; however, we did not observe relevant differences repeating STS measurements on the Au(111) surface with the same or other Mo tips.…”

“…Tips with non-constant LDOS can generate extra features in STS spectra that can make the extraction (through proper so-called "normalization methods" 8 ) of the "true" surface LDOS difficult. 11 A method to avoid this problem is to use tips made of different materials for acquiring dI/dV signals, in order to identify possible tip contributions to the differential conductivity data.…”