Local Investigation of Molecular Magnetism


National Tsing Hua University

     Spring Term 2013 Solid State Physics 2 Course Material
         Wednesday 10.10 - 11.00 & 11.10 - 12.00 Friday 10.10 - 11.00 Room 105

     2012 Solid State Physics Course Material
         Wednesday 10.10 - 11.00 & 11.10 - 12.00 Friday 10.10 - 11.00 Room 019

     2012 Physics Colloquium 12/11/14 Transperencies
     2012 FunMol Bonn 12/10/04 Transperencies

Institute of Physics, Academia Sinica / National Taiwanese University

     2011 Developments in STM

         Announcement  Download

         Lecture One  Download

Scanning Tunneling Microscopy (STM) became a very common technique for the investigation of surfaces. Thereby, most of its fundamental aspects were already established when scientists started to study simple metal-insulator-metal (MIM) junctions in the 60ies and 70ies. Albeit the lack of lateral resolution, these early works in the field of tunneling devices are still an important source for the work with STM. Therefore, this 1st lecture will give an overview on the physical processes indentified, ranging from elastic tunneling to inelastic tunneling in theory and experiment.

Lecture Two  Download

The optimized operation of a Scanning Tunneling Microscopy (STM) requires a thourough understanding of the individual components and their isolation from disturbances from the external world. Today's lecture will cover the mechanical design, the electronic setup, the isolation from mechanical, acoustical, and electronic noise. Focus is not so much the individual detail but the principal concept on how to build a highly sensitive instrument and to sensibilize the audience for sources of noise and their eliminations.

Lecture Three  Download

The technique of Scanning Tunneling Spectroscopy (STS) is the most powerful tool to access electronic, magnetic, vibrational, .... phenomena at the atomic scale by using STM. Conventionally, this is most efficiently realized by employing a Lock-In Amplifier. In todays lecture, the operation of a Lock-In Amplifier is discussed. Goal is, that students become aware that the acquisition time, energy resolution, and signal-to-noise ratio are not arbitrarily chosen but are always a compromise. Properly chosen, the quality of data matches the physical question addressed thereby minimizing the time.

Lecture Four  Download

Spin-Polarized Scanning Tunneling Microscopy is a fascinating tool to access static spins on the atomic scale. First demonstrated more than 20 years ago, the application of SP-STM did not become very common although desired. Required is to have a high-quality sample and a magnetic probe, simultaneously.Thereby, problematic is to identify the problem to be solved when experiments fail as the combination of tip and sample is crucial. In my lecture today, I will discuss the application of SP-STM, the problems, and a way to overcome a fully frustrating time for students in the lab not finding the right approach.

Lecture Four  Download

This final lecture will give an overview on recent developments in the field of STM. The first part will demonstrate the broad range of applications without any further details but solely focused on reading hints. The second part will discuss in greater detail the two most fundamental experiments from the early 90ties, namely manipulation and spectroscopy and reading suggestions for a deeper understanding which will also cover critical aspects problematic in experiments. The application of these two techniques in combination with magnetic spectroscopy in recent work is the central topic of my final part.

University of Hamburg

     SS 2005: Students'Class "Nanotechnology II"
     WS 2005/6: Students'Seminar "Theory and Praxis of Scanning Probe Methods"
     WS 2006/7: Students'Seminar "Theory and Praxis of Scanning Probe Methods"
     SS 2007: Students'Class "Solid State Physics"
     WS 2007/8: Students'Seminar "Magnetism in reduced dimensions"
     2006-2010 SFB 668-Kolloquium „Magnetismus vom Einzelatom zur Nanostruktur“
     2006-2010 SFB 668-Seminar „Magnetismus vom Einzelatom zur Nanostruktur“

University of Kiel

     2000 Medicine Students'Lab
     2001 Medicine Students'Lab

RWTH Aachen

     WS 1996/7 Solid State Students'Lab
     SS 1997 Solid State Students'Lab
     WS 1997/8 Solid State Students'Lab
     SS 1998 Solid State Students'Lab
     WS 1998/9 Solid State Students'Lab
     SS 1999 Solid State Students'Lab
Home © 2010, Dr. Germar Hoffmann nach oben