Facilities and Instrumentation

There are three unique SPMs in my lab: a homemade variable temperature-magnetic force microscope (VT-MFM), an ultrahigh vacuum-low temperature-scanning tunnel microscope (UHV-LT-STM), and a multi-mode (Veeco) atomic force microscope  (AFM).


Our homemade VT-MFM is the only machine in the world that is capable of high spatial resolution magnetic imaging with high sensitivity in a wide temperature range (3-300 K) with in situ high magnetic field (8 T) and high voltage (1 kV). The unique combination of in situ capabilities of our MFM allows us to explore novel magnetic and electric properties of almost any new materials at extreme conditions. Examples include correlated net moments at multiferroic domain walls, magnetic inhomogeneity in ultra-thin magnetic films and unconventional pancake-like domains in multiferroics. In addition, we have developed unprecedented Magnetoelectric Force Microscopy (MeFM) for visualizing magnetoelectric domains with submicron resolution.
 
Description: Description: Description: MFM in SC magnet
Description: Description: Description: MFM head
Key features
•        Var. T (3 – 300 K) & high H (8 T)
•        High vacuum (<1E-6 mbar)
•        High resolution (20-50 nm)
•        High sensitivity (~ )
– Mmin ~
– SC vortics in Ba(Fe,Co)2As2
•        in-situ high voltage (1 kV)
–  10 MV/m for thickness ~ 0.1 mm
–   MeFM
MFM inside 8 T magnet
MFM head





An ultra-high-vacuum low temperature scanning tunnerling microscope (UHV-LT-STM) from Omicron Nanotechnology has been installed in our SPM lab.  The system consists of a LT-STM analysis chamber, and dedicate preparation chamber and a load-lock (FEL). The base pressure of the STM chamber is below 1e-11 mbar. The base temperature is 4.5 K. The dedicate preparation chamber for in situ tip and surface preparation is installed.
In collaboration with Prof. M. Bode at the Universitδt Wόrzburg, we are developing a novel spin polarized-STM (SP-STM) technique to visualize atomic scale magnetic structure in novel magnetic materials.
 
Description: Description: Description: LTSTM Key features
 
•        Ultra High Vacuum (UHV)
–      Pbase < 10-11 mbar
•        Low temperature
–      Tbase ~ 4.5 K
•        Low vibration
–      z noise ~ 1-2 pm
•        Tip/sample preparation
–      Tip prep tool
–      Button heater (1000 °C)
–      Sputter gun
–      RGA
–      Evaporators
–      …
                  UHV-LT-STM  



A multi-mode atomic force microscope (MM-AFM, Bruker) with an extender that is capable of all AFM modes (contact, tapping, PFM, MFM/EFM, SSPM, cAFM, etc.) at ambient condition. The commercial unit is connected with dedicate electric cables for high sensitivity background-free piezoresponse force microscopy (PFM) measurements (~0.1 pm/V with 5 V modulation) using a dedicate lock-in amplifier (SR 830).

MM-AFM

Besides developing experimental tools and techniques in-house, we are also collaborating with facility scientists in the Center for Nanoscale Materials (CNM) at Argonne National Laboratory (ANL) to expand our SPM capabilities by utilizing their advanced SPM instruments.  At the same time, we are implementing various advanced SPM techniques at CNM so that other facility users from the research community can benefit from our SPM expertise.