Direct observation of double exchange in ferromagnetic La0.7Sr0.3CoO3 by broadband ellipsometry
|Year of publication
|Article in Periodical
|Magazine / Source
|Physical Review B
|MU Faculty or unit
|double exchange; ellipsometry; ferromagnetic cobaltites; La0.7Sr0.3CoO3;
|We present results of our broadband ellipsometry measurements of the optical response of ferromagnetic La0.7Sr0.3CoO3. Our data show that the ferromagnetic transition is accompanied by a transfer of optical spectral weight from an absorption band centered at 1.5 eV to a narrow component of the Drude-like peak. The associated reduction of the intraband kinetic energy is significantly larger than k(B)T(c), confirming that the double exchange plays a major role in the ferromagnetism of doped cobaltites. In conjunction with results of recent theoretical studies, the temperature dependence of the Drude-like peak suggests that the double exchange is mediated by t(2g) orbitals.