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Finally, in the past decade, direct computation or simulation has become an increasingly routine and reliable method for seeing and understanding condensed matter.

This chapter consists of sections devoted to each of the tools noted. Each section describes specific accomplishments these tools made possible in the last decade as well as opportunities and challenges for the future. Even though the sections deal with quite distinct facilities and techniques, there are certain overarching themes. An excellent example of an important scientific contribution over the last 10 years has been the effort to unravel the astonishing properties of the high-Tc cuprates and their siblings. It would be very difficult to imagine where our knowledge of the cuprates would be without the atomic coordinates given by neutron diffraction carried out at proton accelerators, the electronic bands given by photoemission at synchrotron sources, the defects found by electron microscopy, the magnetic order and fluctuations discovered using both reactor- and accelerator-based neutron sources, the charge transport measured in extreme pressures or magnetic fields, and the computer calculations of electronic energy levels. The experience with the cuprates shows that each of the facilities used is both unique and indispensable, and that their power is vastly amplified by combining data from the entire suite.

In addition to addressing specific scientific problems, another overarching theme includes the invigorating effects of new facilities, be they large national resources such as the Advanced Photon Source, the new hard x-ray synchrotron at Argonne National Laboratory; medium-scale installations such as the newly formed National High Field Magnet Laboratory operated in Florida and New Mexico; or electron microscopes and surface characterization equipment in central materials research facilities. The commercial availability of increasingly powerful workstations, electron microscopes, piezoelectric scanning-probe tools, and superconducting magnets have played an equally important but different role—namely, that of democratizing access to atomic resolution and high magnetic fields by giving individual investigators with small laboratories extraordinary capabilities formerly limited to those with access to large facilities.

A final thread linking the tools is a direct product of the information revolution seeded by condensed-matter physics and discussed at length elsewhere in the report—specifically, the proliferation of information the tools provide and the increasingly quantitative nature of the information. The most obvious manifestation is the trend away from simple black-and-white x-y plots and toward digital color images as experimental outcomes. Such images were exotic and laboriously produced 10 years ago. (The original scanning-tunneling microscopy images of silicon surfaces by Binnig and Rorer were actually photographs of cardboard models constructed from chart-recorder traces.) Today, color images are a routine feature of output from all of the techniques and facilities described below.

The future holds many opportunities and challenges including raising probe particle brilliance, improving instrumental resolution, extending spectral ranges,



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