Highlights

Electron paramagnetic resonance (EPR) is commonly used to manipulate and measure the magnetic moments (or spins) of electrons.  IRG-D researchers at the Princeton Center for Complex Materials (PCCM) have demonstrated a 100 fold improvement in sensitivity to the electrons’ spins by combining long-coherence donor electrons in isotopically enriched silicon with superconducting Nb microresonators.1  The PCCM researchers have previously shown that these donor impurities, each binding one electron, exhibit exceptionally

Block copolymer thin films are effective templates for fabricating large arrays of nanoscopic objects; for example, polymers which self-assemble into cylinders lying in the plane of the film yield striped patterns, which can be replicated in metal to yield nanowire grids which effectively polarize the short-wavelength ultraviolet light used in today’s advanced production photolithography.   But other applications demand more perfect order of the striped-pattern template:  perfectly straight and unbroken wires. 

Processed NW network

Fig. 1 Device schematic, optical micrograph, and initialization scheme.

Thin block copolymer films are highly relevant for many scientific and industrial applications due to their ability to form uniform domains of controllable shape at nanometer length scales. From a technological point of view, the cases of shapes with long axes may be of interest in the fabrication of nanowires, while upright cylinders and spheres could have potential applications in the patterning of hexagonal arrays for data storage.

We investigated the electronic properties of interfaces between two laminated polymer films. The top polymer film (Fig. (a)) is transferred to a soft PDMS stamp, and laminated against the bottom film, previously spin-coated on a substrate. Using electron spectroscopy and Kelvin micro-probe techniques, we demonstrated that the process does not introduce any molecular shift due to interface dipole or surface states. We also showed that the interface is transparent to charge carrier transport, as shown in Fig. (b).

Studying the electronic properties of the surface states on Topological Insulators requires high quality bulk crystals. We have figured out the defect chemistry of these compounds and grown crystals by the Bridgman Stockbarger method.