Alex Zettl

Research Expertise and Interest

physics, condensed matter physics, fullerenes, condensed matter experiments, characterize novel materials with unusual electronic and magnetic ground states, low-dimensional and nanoscale structures, superconductors, giant magnetoresistance materials, nanotubes, graphene, boron nitride nanostructures, neural probes, NEMS.

Research Description

Alex Zettl's research interests are in experimental condensed matter physics. His research group synthesize and characterize novel materials with unusual electronic and magnetic ground states, including low-dimensional and nanoscale structures. Examples are charge- and spin-density-wave conductors, superconductors, giant magnetoresistance materials, fullerenes, and nanotubes. Experimental characterization techniques include structural measurements (TEM, X-ray scattering) and the examination of general transport coefficients (dc and high frequency conductivity, Hall effect, thermal conductivity, thermopower), high magnetic field studies, high pressure effects, and velocity of sound. In addition they operate a high magnetic field cryogenic STM capable of manipulating and assembling individual atoms into interesting structures.

Current Projects

High-temperature superconductors: They synthesize polycrystalline, single crystal, and thin film and superlattice specimens of high-Tc oxide superconductors such as Y-Ba-Cu-O, Bi-Sr-Ca-Cu -O, and Hg-Ba-Ca-Cu-O, and perform isotope effect, intercalation, and magnetotransport studies. The goal is to understand the normal state transport and the mechanism of superconductivity. New superconductors have been synthesized and are being used to test theoretical models. Vortex (Abrikosov and Josephson) dynamics are studied in applied magnetic fields to 17.5 Tesla.

Fullerene-based conductors and superconductors: Fullerenes such as the soccer-ball-shaped molecule C60 are the basis for interesting conductors and superconductors. THey intercalate C60 single crystals with alkali metals and study isotope effects (both alkali and cabon), general transport, magnetotransport, and high pressure effects. The C60 molecules can be polymerized into quasi-one-dimensional chains. These new air-stable conducting crystals display unusual phase transitions that they examine via conductivity, specific heat, x-ray scattering, and STM.

Nanotubes: It is possible to arrange carbon atoms into near-perfect nanotubes structures with diameters on the order of 10Å to 1000Å and lengths over 100µm. Theoretically, these tubes are the strongest possible fiber, and they are predicted to have unusual electronic properties (some are conductors, others insulators). They fabricate carbon nanotubes and measure their structure via TEM and electrical and mechanical properties using other techniques. It is possible to fill the tubes with other atoms, and to collapse the tubes into flat, flexible ribbons. In addition, it has been predicted that nanotubes containing boron and nitrogen, BxCyNz, may have many properties superior to carbon nanotubes for applications purposes. They synthesize such tubes and study their properties.

Giant magnetoresistance materials: Materials such as La-Ba-Mn-O are semiconductor-like at high temperature and metal-like (with magnetic ground states) at low temperature. In the intermediate temperature regime (typically somewhat below room temperature), they may display an unusually large negative magnetoresistance. They study the magnetoresistance and other transport properties in order to understand the conduction and scattering mechanisms.

Atomic-scale manipulation: They have designed and constructed a unique high-speed, high-field, cryogenic UHV scanning tunneling microscope capable of assembling and measuring the electronic properties of nanoscale structures, including superconductors and nanotubes.

In the News

Physicists snap first image of an ‘electron ice’

More than 90 years ago, physicist Eugene Wigner predicted that at low densities and cold temperatures, electrons that usually zip through materials would freeze into place, forming an electron ice, or what has been dubbed a Wigner crystal. While physicists have obtained indirect evidence that Wigner crystals exist, no one has been able to snap a picture of one — until now. UC Berkeley physicists published last week in the journal Nature an image of just such an electron ice sandwiched between two semiconductor layers. The image is proof positive that these crystals exist.

A graphene innovation that’s music to the ears

For lovers of high-fidelity audio, or for those who just want the coolest new thing, revolutionary, distortion-free earphones based on high-tech graphene will soon be coming your way, courtesy of basic research at UC Berkeley and Berkeley Lab.

Bats do it, dolphins do it. Now humans can do it too.

UC Berkeley physicists have used graphene to build lightweight ultrasonic loudspeakers and microphones, enabling people to mimic bats or dolphins’ ability to use sound to communicate and gauge the distance and speed of objects around them.

Scientists benefit as much as students from "Cleantech to Market" program

Launched as a pilot project at Berkeley Lab, the Cleantech to Market program is finishing its first semester as an official class at UC Berkeley's Haas School of Business, and it's safe to say the students learned more than they expected on how to take a technology from the laboratory to the marketplace. What was less expected is how much the scientists got out of the program.

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