SYNCHROTRON-BASED STUDIES ON CUPRATES AND MANGANITES: ELECTRONIC AND MAGNETIC CORRELATIONS

Abstract

THE STRONG CHARGE-SPIN-ORBITAL-LATTICE COUPLINGS IN STRONGLY CORRELATED SYSTEMS HAVE LED TO SOME EXCITING PHENOMENA IN CONDENSED MATTER PHYSICS. CUPRATES AND MANGANITES, THE TWO WELL-STUDIED MATERIALS, CONTINUE TO PRESENT RICH PHENOMENA AND NEW CHALLENGES. THIS THESIS FOCUSES ON THE STUDY OF ELECTRONIC AND MAGNETIC STRUCTURES OF CUPRATES AND MANGANITES USING SYNCHROTRON BASED X-RAY ABSORPTION NEAR EDGE SPECTROSCOPY (XANES), X-RAY MAGNETIC CIRCULAR DICHROISM (XMCD), X-RAY DIFFRACTION (XRD), SPECTROSCOPIC ELLISOMETRY (SE) AND OTHER COMPLEMENTARY METHODS. THE CUPRATES WERE STUDIED BY USING A COMBINATION OF XANES AND SE. THE EVOLUTION OF ELECTRONIC BAND STRUCTURES AS A FUNCTION OF DOPING FOR SERIES OF HOLE AND ELECTRON DOPED Y0.38LA0.62(BA0.82LA0.18)2CU3OY (YLBLCO) FILMS WAS STUDIED. FURTHERMORE, A MID-GAP STATE ACCOUNTING FOR THE CO-EXISTENCE OF A LOW ENERGY ANTIFERROMAGNETIC STATE AND A MOTT STATE IN AMBIPOLAR CUPRATES YLBLCO, WAS DISCOVERED AND INVESTIGATED THROUGH A THEORETIC