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Yazdani finds superheroes under his own microscope.

Ali Yazdani began his career as a teenage television repairman in Iran. But, after he emigrated to the United States, a course in quantum mechanics pulled him into science.

In 2008, Popular Science magazine named him one of the Brilliant Ten, the top brains under the age of 40 in the science world.

Now a physicist at Princeton University, he's overturned the accepted thinking on high-temperature superconductors with a desk-size scanning-tunneling microscope. It can cool a sample to just above absolute zero, seal it in a near-perfect vacuum, and block the faintest noises. As a result, he can continuously track single atoms for months at a time.

He leads a Princeton team that has now found that electrons on the surface of specific materials act like miniature superheroes, relentlessly dodging the cliff-like obstacles of imperfect microsurfaces, sometimes moving straight through barriers like Superman plunging through a wall. That pioneering work is reported in the July 15 issue of Nature magazine.

Yazdani, who was born in Tehran in 1967, told Popular Science magazine his interest in science began as a teenager in Iran when he enrolled in a class on how to repair television sets. After moving to the United States after high school in 1984, a course in quantum mechanics at the University of California at Berkeley peaked his interest in physics.

Yazdani told the Iran Times, "I was always interested in science as a kid in Iran, but it was my year at UC Berkeley that got me interested in physics. I took a course on quantum mechanics and decided to do physics instead of engineering."

He subsequently went on to earn his Ph.D. from Stanford University in 1995. He served on the physics faculty of the University of Illinois-Urbana from 1997 until 2005, when he moved to New Jersey to join the faculty at Princeton.

The "brilliant" Iranian's research has disproved long-held beliefs on high-temperature superconductors with provoking results based on two years of experiments he led with his research group at Princeton. In one experiment, he and his group proved that high-temperature superconductivity does not hinge on a magical glue binding electrons together. The secret to superconductivity may rest instead on the ability of electrons to take advantage of their natural repulsion in a complex situation.

Yazdani conducts his research at Princeton's Nanoscale Microscopy Laboratory, a state-of-the-art, ultra-low-noise lab. Yazdani and his group study condensed matter physics, searching for simple, unifying explanations for complicated phenomena observed in liquids and solids.

Princeton says this work represents the first time such behavior of electrons has been tracked and recorded, and hints at the possibilities of speeding up integrated circuits that process information by the flow of electrons among different devices. The new materials potentially could break the bottleneck that occurs when metallic interconnects get so small that even the tiniest atomic imperfection hinders their performance.

In his latest work, described in the current Nature magazine, Yazdani and his team at Princeton observed the extraordinary physics behavior in a "topological surface state" on a microscopic wedge of the metal antimony.

Normally, electron flow in materials is impeded by imperfections--seemingly slight edges and rifts that act like cliffs and crevasses in this microscopic world, blocking electrons in their path. Recent theories, however, predict that electrons on the surface of some compounds containing elements such as antimony can be immune to such disruptions in their flow. The connectivity in their flow, Yazdani said, stems from a special form of electron wave that seemingly alters the pattern of flow around any imperfection.

Part of the challenge had been the difficulty in measuring the flow of electrons on the surface, a task that was accomplished by Yazdani's group using a specialized microscopy technique that enables precise visualization of electrons at the surface of materials.

Because the electrons are able to move freely on the surface of the experimental material regardless of the shape of that surface, the material has a "topological surface state," Yazdani said. Topology is a major area of mathematics concerned with spatial properties that are preserved despite deformation, like stretching. In that regard, a doughnut and a coffee cup can be viewed as topologically the same because they both are essentially areas with holes in the middle.


With lab instruments, Yazdani's team was able to measure how long electrons are staying in a region of the material and how many of them flow through to other areas. The results showed a surprising efficiency by which surface electrons on antimony go through barriers that typically stop surface electrons of most conducting materials, such as copper.
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Title Annotation:Diaspora: Around the globe
Publication:Iran Times International (Washington, DC)
Date:Jul 23, 2010
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