4 papers
Revisiting the Froehlich-type transformation when degenerate states are present
M. Acquarone, C. I. Ventura
We focus on the definition of the unitary transformation leading to an effective second order Hamiltonian, inside degenerate eigensubspaces of the non-perturbed Hamiltonian. We sha…
Magnons in CMR pyrochlore Tl2Mn2O7
C. I. Ventura, M. Acquarone
Well defined spin waves were observed when the spin dynamics of Tl2Mn2O7, the first pyrochlore compound found to exhibit colossal magnetoresistance, was measured [J.W.Lynn et al.,…
Towards an understanding of CMR pyrochlore Tl2Mn2O7
C. I. Ventura, M. A. Gusmao, .
Tl2Mn2O7 exhibits important differences with other colossal magnetoresistance (CMR) compounds, like the Mn-perovskites, in its crystal structure and electronic properties, indicati…
Intermediate Valence Model for Tl_{2}Mn_{2}O_{7}
C. I. Ventura, B. R. Alascio
There have been speculations about the need to find a new mechanism to explain the colossal magnetoresistance exhibited by this material, having pyrochlore structure and thus diffe…