Design Rules for Manganites with Novel Magnetic and Electronic Properties
Northern Illinois University (NIU), Faraday Hall W216, De Kalb, Il 60115, United States
We have been systematically developing strategies for making new perovskite manganites with novel magnetic and electronic properties. This effort requires two-fold approach: development of understanding the dependence of properties on chemical and structural factors and development of ability for synthesis of desired compounds. We show that similar to other single valent 3d systems the magnetic superexchange interactions in RMnO3 manganites (R = Rare or Alkaline Earth's) are dependent on the Mn-O-Mn bond angle that is a function of interatomic distances R-O and Mn-O. The local structural disorder on the R-site suppresses magnetic interactions. Recently, by comparing disordered (randomly mixed R/Ba) and ordered (forming Ba/R/Ba layers along the c-axes) perovskites we have demonstrated much more conspicuous effects of structural and charge disorder for mixed-valent manganites. We show that by stabilizing ordered structure; i.e., by suppressing local structural and charge disorder, for R = La and Pr a substantial increase of Tc (from 340 and 200 to 365 and 335 K, respectively) can be achieved.
Presentation: invited oral at E-MRS Fall Meeting 2003, Symposium D, by Bogdan Dabrowski
See On-line Journal of E-MRS Fall Meeting 2003
Submitted: 2003-05-16 21:23 Revised: 2009-06-08 12:55