State of the Art Atomic Force Microscopes (AFM) and their relatives in 20mK-300K Temperature Range
Abstract: We will give an overview of the state of the art Atomic Force Microscopes (AFM) in the 20mK to 300K temperature range. Recent developments in cryofree cryostats and dilution refrigerators (DR) have opened a new avenue for scientists suffering from heavy Helium costs. We shall first describe the design of High Resolution MFM which can achieve 10nm magnetic resolution. Such high resolution is possible with unprecedented ~12fm/√Hz noise floor of the cantilever deflection electronics.
We shall also describe a mK-Scanning Probe Microscopes (mK-SPM) operating in Scanning Tunnelling Microscope (STM), Scanning Hall Probe Microscope (SHPM) and Atomic/Magnetic Force Microscope (AFM/MFM) mode in a wide temperature range of 20mK-300K. We have also designed a Fabry-Perot interferometer for our mK-AFM which has a measured ~8 fm/√Hz noise level at 300K, while the shot noise limit was <1fm/√Hz. The system uses a dielectric multilayer coating at the end of the fiber to achieve this unprecedented noise level. We hope to improve the noise levels further and achieve better than 5-6nm resolution for mK-MFM.
We shall show the initial results on single layer graphene Hall sensors developed for low temperature SHPM imaging between 3-300K. Non-contact mode of operation (nc-AFM) enabled AFMs to achieve atomic resolution in liquids. We shall show recent results on dissolution of Gypsum observed with ncAFM in water.
Last but not the least; we will also describe an affordable tapping mode AFM, ezAFM for teaching & undergraduate labs, industry and research. The ezAFM has 40 mm or 120 mm XY scan range and an integrated 1mm resolution optical microscope. A modern FPGA and 24Bit ADC/DAC converters are used for digital control of all the microscope functions.
Reminder: Tea and cookies will be in the seminar room before the seminar.