Yazdani Group at Princeton University Home Highlights About Research Correlated Electrons Single Spins 2D Superconductors People Publications Internal

PNML Princeton Nanoscale Micrscopy Laboratory Our Research Instrumentation LTSTM VTSTM Dilution Fridge Millikelvin STM Our goal as a group is to study questions of fundamental significance in condensed matter physics using state-of-the-art experimental techniques. Our current activities include atomic scale imaging and spectroscopy of correlated electronic states, probing and manipulating single spins, and examining properties of two-dimensional superconductors. Many of our investigations are being carried out using high resolution scanning tunneling microscopy (STM) instruments that we have constructed over the years in our laboratory. These are housed in PNML. In fact, a common research approach in our group is to design unique instrumentation that enables measurements of electronic phenomena in new experimental regimes (such as measurements on finer length scale, or at extremes of temperatures or magnetic fields). With these new experimental tools, we either search for new phenomena by probing well-established condensed matter systems with finer accuracy or by studying new material systems, which exhibit new properties that challenge our current understanding of electronic phenomena in solids. The Space The Space Located in basement of Jadwin Hall, PNML is a state-of-the-art laboratory designed for high precision measurements in condensed matter physics. This space houses a host of different instruments including scanning tunneling microscopes (STM) that have been moved from the University of Illinois at Urbana-Champaign, where our group had been from 1998 to the summer of 2005. The new space is designed with three ultra-quiet rooms, which consist of double wall enclosures built around a massive plinth that is floating to isolate the experiments. Such a design leads to substantial reductions of both acoustic noise (because of the double enclosure) and seismic vibration (by floating the massive 35 Ton floors). One of these ultra-quiet rooms also has radio frequency shielding to make it possible to carry out experiments which are sensitive to radio frequency interference. Overall, the combination of acoustic, vibrational, and RF isolation make this an ideal space for a host of experiments in physics, including high resolution microscopy and spectroscopy measurements with STMs. The lab space has been designed in collaboration with Wilson Architects. Instrumentation In general our group's research approach combines the development of novel instrumentation and its applications to important problems in physics. Over the years our group has developed several different high resolution scanning probe microscopy instruments and used them to attack a wide range of problems in condensed matter physics. We plan to continue this approach, developing even more advanced instrumentation. LTSTM Room Schematic LTSTM The first instrument built in our lab is an ultra-high-vacuum (UHV) scanning tunneling microscope (STM) designed to operate down to 4 Kelvin. In addition to its unique features, such as its ability to manipulate individual atomic adsorbates, this STM system is equipped with standard surface science tools, such as Auger and low energy electron diffraction (LEED) spectroscopy, as well as evaporation sources for thin-film growth. The system is designed to allow the manipulation of samples between different parts of the chamber to perform surface characterization and measurements. We can perform surface characterization of the samples’ cleanliness and crystalline order with standard surface analysis tools. The samples can be transferred to the microscope chamber onto the STM sample stage, where measurements are performed. With the sample at low or high temperatures, we have the ability to dose the sample with a variety of metal and gas atoms from pure sources. This instrument has been used for a variety of studies including high temperature superconductors, carbon nanotube systems, noble metal surfaces (Kondo studies), and single spins as dopants in semiconductors. VTSTM VTSTM Microscope Microscope Head Schematic We have also constructed two variable temperature STM's capable of performing measurements in UHV from room temperature down to 10K. This system is equipped with both sputtering and evaporation sources for in situ preparation of ultra-thin films. A great deal of care has gone into the design of this system to ensure thermal compensation, so as to avoid typical problems associated with thermal drift. This instrument has been specifically designed to be able to track the same area of a sample surface at atomic scales as we vary the temperature. In this system we also have the added versatility to exchange STM tips without venting the UHV system. This apparatus, with its ability to perform STM over a wide range of temperatures, is being used extensively in our investigations of correlated electronic states. In general we plan to use these instruments to study a variety of phase transition phenomena.