20 March 2008

Magnet Lab researchers produce two of 2007’s top physics papers

Contact: This email address is being protected from spambots. You need JavaScript enabled to view it.

TALLAHASSEE, Fla. — Collaborative groups based at the Tallahassee and Los Alamos branches of the Magnet Lab authored two of the year's most influential physics papers, according to the editors of the Journal of Physics: Condensed Matter. Each year, the journal selects a small group of its most groundbreaking and popular published papers, highlighting physics advancements and trends.

Magnet Lab Seaborg Postdoctoral Associate Susan Cox, based at the Pulsed Field Facility in Los Alamos, is first author on "Evidence for the charge-density-wave nature of the stripe phase in manganites," in which heat capacity measurements of manganite compounds were analyzed.

Cox, LANL Fellow John Singleton and Peter Littlewood, who holds positions at Cambridge University and the Magnet Lab, collaborated with a group from Edinburgh, Scotland. Having such a range of chemistry and experimental and theoretical physics expertise available allowed the authors to pick the three compounds that would reveal the most about manganite behavior. This analysis revealed that the transition at which the stripe phase appears in manganites can be accurately modeled as a Peierls transition in a disordered system. This is the behavior expected of a charge density wave, in contrast to the previously accepted picture of charges localized at atomic sites.

"I am thrilled that our paper was selected by JPCM," said Cox. "Our conclusion that the transition in manganites is driven mainly by a Fermi surface instability is very exciting, and it's great to see the importance of this idea recognized."

Magnet Lab Postdoctoral Associate Haidong Zhou is first author on "The origin of persistent spin dynamics and residual entropy in the stuffed spin ice Ho2.3Ti1.7O(7-d)," in which he showed that stuffing spin ices with extra spins appears to lead to new magnetic phases. In addition to its designation as a Top Paper, the work was presented as an invited talk at the International Conference on Crystal Growth held in Utah last year.

"These systems are interesting because they apparently violate the third law of thermodynamics – there is a significant amount of residual entropy at very low temperatures," said Florida State University Assistant Professor Chris Wiebe, who collaborated on the project. "This is yet another example of how key discoveries can be made using the resources at the Magnet Lab and other National Science Foundation-supported laboratories such as the Center for High Resolution Neutron Scattering at NIST."

In addition to Wiebe, Postdoctoral Associate Youn-jung Jo, Associate Scholar/Scientist Luis Balicas, Graduate Research Assistant Jing Jing Qiu, National Institute for Science and Technology (NIST) staff Yiming Qiu, John Copley, and Jason Gardner, Peter Fouquet at the Institut Laue-Langevin, and Georg Ehlers at the Spallation Neutron Source all also collaborated on the project. The very first crystals of this new "stuffed spin ice" compound were grown locally at the Magnet Lab using the floating zone image furnace in the Quantum Materials lab of Wiebe.