During September 2006 -August 2007 period the PI pursued two main avenues of research. First one concentrates on the physics of magnetite (Fe₃O₄), and the second one deals with the transition metal tellurite halides which is a family of compounds with the fascinating magnetic properties.   During 2006-2007 two undergraduate students (Victoria Martin and Jason Saredy) we supported by this grant and two more students (James Tracy and Young Ge) were supported by the PI's Research Corporation award. 

Magnetite: Magnetite (Fe₃O₄) is an example of the Correlated Electron Materials. These materials represent an intermediate case of the electronic structure of solids between those that have itinerant electrons and those with localized electrons. Raman spectra of optimally doped magnetite (Fe₃O₄) single crystals reveal broad electronic background extending up to 900 wavenumbers (~110 meV).  Redistribution of this background is observed (Fig.1) when sample is cooled below the Verwey transition temperature (T_V= 123K). In particular, spectra of the low temperature phase show diminished background below 300 wavenumbers followed by an enhancement of the electronic background between 300 and 400 wavenumbers with subsequent decrease of the background below 400 wavenumbers,. Such redistribution may be assigned to an opening of the charge gap at about 350 wavenumbers (43 meV). The value of the gap is within the range of the photoemission data on freshly fractured magnetite sample.

Transition metal tellurite halides: Transition metal tellurite halides Co₅(TeO₃)₄Br_2, Co₇(TeO₃)₄Br₆ are  novel layered materials with low dimensional magnetic ordering and strong anisotropy of magnetic susceptibility. Both Co₇(TeO₃)₄Br₆ and Co₅(TeO₃)₄Br₂  demonstrate Currie-Weiss temperature behavior of susceptibility at high temperatures followed by magnetic ordering at 35K and 16 K respectively. My students and I are currently going through the exploratory phase of the project. We are studying the evolution of the electronic, orbital, spin and lattice excitations as the systems go through the magnetic ordering.

Additional funding: The PI continues to look for possible additional sources of funding. Currently the PI has two more active grants:

Title:                                         Raman and Infrared studies of the Layered Transition Metal Chalcogenides

Source of support:                    Research Corporation Cottrell College Science award

Dates of support:                      5/11/2004-5/10/2009

Total amount of award:             $40,384

Title:                                         Advancing Chemical Sensors

Source of support:                    Office of Naval Research, Department of the Navy

Dates of support:                      10/26/2005-12/31/2007 (extended)

Total amount of award:             $859,060 (Co-Pi with Dr. J. Huebner)

Summary:

Student working with the PI:                             four (two supported by this award)

Peer-reviewed publications:                              one

Conference talks:                                              two

External funds in addition to the PRF award: $899,444