13-19 June 2015
University of Alberta
America/Edmonton timezone
Welcome to the 2015 CAP Congress! / Bienvenue au congrès de l'ACP 2015!

Terahertz Scanning Tunneling Microscopy in Ultrahigh Vacuum

16 Jun 2015, 14:45
15m
NINT Taylor room (University of Alberta)

NINT Taylor room

University of Alberta

Oral (Student, In Competition) / Orale (Étudiant(e), inscrit à la compétition) Condensed Matter and Materials Physics / Physique de la matière condensée et matériaux (DCMMP-DPMCM) T2-1 Materials characterization: microscopy, imagining, spectroscopy (DCMMP) / Caractérisation des matériaux: microscopie, imagerie, spectroscopie (DPMCM)

Speaker

Mr Vedran Jelic (University of Alberta)

Description

The terahertz scanning tunneling microscope (THz-STM) is a new imaging and spectroscopy tool that is capable of measuring picosecond electron dynamics at the nanoscale. Free-space THz pulses are commonly used for non-contact conductivity measurements, but they are diffraction limited to millimeter length scales. We can overcome this limit by coupling THz pulses to a sharp metal tip through propagating surface modes. At the STM junction, the THz pulse acts as a picosecond voltage transient which drives electron tunneling on an ultrafast timescale. This effect can be used to spatially and temporally probe the local conductivity of a surface after an excitation. Here we demonstrate THz-STM in an ultrahigh vacuum (UHV) environment for the first time. We have measured a THz-induced-tunnel-current over highly-oriented pyrolytic graphite (HOPG), and Si(111) in UHV. The experimental results agree well with our model, providing insight for the THz-STM mechanism. Recent progress towards atomic resolution and the nature of THz-induced-tunneling in an STM will be presented.

Primary author

Mr Vedran Jelic (University of Alberta)

Co-authors

Prof. Claus Ropers (University of Göttingen) Prof. Frank Hegmann (University of Alberta) Ms Haille Sharum (University of Alberta) Mr James Hoffman (University of Alberta) Prof. Mark Freeman (University of Alberta) Mr Peter Nguyen (University of Alberta) Mr Rathje Christopher (University of Göttingen)

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