טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentMarcipar Goldstein Lital
SubjectThe Ground State and Excitation of the Spin 1/2 Kagome
Lattice
DepartmentDepartment of Physics
Supervisor Professor Amit Keren
Full Thesis textFull thesis text - English Version


Abstract

The experimental search for an ideal two dimensional, spin 1/2, Kagome compound, which has no out-of-plane interactions and no impurities on the Kagome plane, has powered tremendous experimental efforts in recent years. Recently a new Kagome compound was synthesized. New organometallic hybrid compound Cu(1,3-benzendicarboxylate) [Cu(1,3-bdc)], which has structurally spin 1/2 copper Kagome planes separated by pure organic linkers. Using muon spin resonance, magnetization measurements and electron spin resonance (ESR) we examine this new Kagome. Susceptibility and ESR measurements revealed distinct anisotropy behavior. By orienting the sample two different Curie-Weiss temperatures are found. When the applied external field is parallel to the Kagome planes, Curie-Weiss temperature in the z direction exhibits ferromagnetic interactions. As for the perpendicular direction, Curie-Weiss temperature is not reliable, thus we cannot characterize the interactions in the Kagome planes from magnetization measurements alone.

Furthermore, ESR measurements done on the Cu(1,3-bdc) compound reinforced the presence of anisotropy. We get two different g-factors for each direction measured and two different ESR line-widths, which were found out to be temperature independent.

Susceptibility and ESR measurements combined with theoretical calculations allow us to characterize the spin Hamiltonian.

From the muon spin resonance experiment we found slowing down of spin fluctuations starting at T = 1.8 K, and that the state at T à 0 is quasi-static with no long-range order and extremely slow spin fluctuations at a rate of 3.6 sec-1.

This indicates that Cu(1,3-bdc) behaves as expected from a Kagome compound.