Structural study of High Tc Superconductor exfoliated nanocrystals

We demonstrate that structural and spectroscopic information can be obtained on exfoliated nanocrystals as thin as 6nm. This can be achieved by using a combination of micro X-ray fluorescence (lXRF), micro X-ray absorption near-edge spectroscopy (lXANES), and X-ray microdiffraction (lXRD) techniques. Highly focused, tunable X-ray beams available at synchrotron sources enable one to use these non-invasive characterization tools to study exfoliated samples on a variety of substrates. As an example, we focused on exfoliated nanocrystals of the high temperature superconductor Bi2Sr2CaCu2O8þd. lXRF is used to locate the sample of desired thickness; lXANES and lXRD are used to obtain electronic and structural information, respectively. We find that the “4.7b” structural modulation, characteristic of the bulk crystals, is drastically suppressed for exfoliated crystals thinner than 60 nm.

A. Lupascu et. al, APL 101, 223106 (2012)