Colossal magnetoresistive manganites and high temperature superconductors: so different, yet so similar – Norman Mannella

Date: Thu. February 1st, 2007, 4:15 pm-5:15 pm
Location: Rockefeller 301

Transition metal oxides constitute a prototype for complex electron systems in which electrons organize collectively and give raise to spectacular macroscopic properties, with the most prominent examples being high temperature superconductivity and colossal magnetoresistance. The study of these systems has to date unveil a common motif which is becoming a paradigm in condensed matter physics: the interplay and competition of multiple degrees of freedom like charge, lattice and spin.

In this talk, I will provide a compelling example of this paradigm by discussing the results of some recent angle-resolved photoemission spectroscopy (ARPES) investigations in the prototypical colossal magnetoresistive compound La1.2Sr1.8Mn2O7. Its electronic structure has been found to be strikingly similar to that of the pseudogap phase in heavily underdoped cuprates high temperature superconductors, in which quasiparticles are found only along certain crystallographic directions but not along others. Besides discussing the implications of these findings, I will also address another commonality with the high temperature superconductors consisting in the unexpected manifestation of collective effects in a single particle spectroscopy like ARPES. This phenomenology suggests that coherence-driven transitions are a common denominator for the high temperature quantum phenomena in transition metal oxides.