# Presentation: 740253

## Infrared Spectroscopy of High-Tc Superconductors 

**Publications: **
***Phys. Rev. B 72, 054529 (2005)***
***Phys. Rev. B 72, 172511 (2005)***
***Phys. Rev. Lett. 96, 17403 (2006)***
***Annalen der Physik 15, 545 (2006)***

**Infrared Spectroscopy of High-Tc Superconductors**** **
**D.N. Basov,  *****UCSD*****  ****	****	****	****	****	****            DMR 0240194**

- A schematic diagram of the state-of-the-art instrument for infrared magneto-optical studies of superconductors and other novel materials built at UCSD by graduate and undergraduate students working in the laboratory of the PI [*W.J. Padilla et al.  Rev. Sci. Instr. 75, 4710 (2004*)]. Recent work on the pairing mechanism would not have been possible without this apparatus. Next page shows a photograph of the actual apparatus along with the key contributors to this work.

**Notes:**
	Electron pairing in conventional superconductors (Al, Pb, etc) is mediated by the crystal lattice. The origin of the pairing interaction in high-Tc superconductors is yet to be identified. Numerous experiments suggest that the nature of the pairing “glue” in these high-Tc materials may be related to the magnetic degrees of freedom and not to the lattice. The PI has carried out a series of experiments aimed at critical tests of this intriguing hypothesis. 
	The idea of an experiment is the following. Neutron scattering studies have established that a magnetic resonance believed to mediate pairing in new oxide superconductors is suppressed by the applied magnetic field. One can readily estimate expected changes in infrared properties of these crystals assuming that the magnetic resonance is indeed responsible for pairing. The effect is small but falls well within the reach of the new apparatus developed in the laboratory of the PI. Careful studies of the magnetic field dependence of IR properties convincingly show the insenstivity of the particular IR features to the magnetic field. This is in stark contrast with the expectations of theories of magnetically driven superconductivity. 
	Before ruling out the magnetically driven scenario it is imperative to refine neutron scattering studies serving as the foundation of this experimental approach. Motivated by new experiments of the PI this work is currently under way in several neutron scattering groups.       

## Infrared Spectroscopy of High-Tc Superconductors 

**Infrared Spectroscopy of High-Tc Superconductors**** **
**D.N. Basov,  *****UCSD*****  DMR 0240194**

**	**The diagram on the right is taken from the 2003 nugget submitted by the PI with the goal to illustrate by example the broader impact of the NSF funding.
**	**_**Front: Willie Padilla**_**, **first came to UCSD as a summer student in 1999. He completed thesis work in the group of the PI in 2004.  In 2006 he joined the faculty of Boston College as an assistant professor. ** **
**	**_**Right: Jason Singley and Sasa Dordevic**_** **completed their thesis work in the group of the PI in 2002. Currently, Dr. Singley is an assistant professor with Cal.State and Dr. Dordevic is an assistant professor at the University of Akron.
**	**_**Back: Kenneth Burch**_**, **first joined the group of the PI as an REU student in 2000. His thesis work with the PI has resulted in the Best Thesis Award from the American Physical Society. Currently, he is a Director’s postdoc at LANL.

**Notes:**
	The PI strongly believes in the value of undergraduate research. In his experience, summer research programs have helped to jump start careers of many motivated students. For this reason the PI devotes a significant amount of his time and effort to work with undergraduates at UCSD using every possible format including: i) NSF-funded REU program (he serves as the PI); ii) McNair program offering mentoring and research opportunities to first generation college students; iii)  CAMP (California Alliance for Minority Participation)  by mentoring several program participants, and finally iv) by offering research positions in his group to driven and talented undergrads. 
	Among many success story few stand out. For example, Willie Padilla first became affiliated with the group of the PI through the McNair program. After completing his thesis work in the group of the PI he was offered a prestigious Director’s fellow position at Los Alamos National Laboratory. In 2006 he received numerous job offers for assistant professor positions before finally deciding on joining physics department at Boston College. 
	The PI has extensively published with undergraduates: during the current support period he published 5 articles with undergraduate co-authors in refereed journals including 2 in Physical Review Letters.