PGI-1 Seminar: Dr. Priya Mahadevan
Orbital ordering in transition metal oxides - a route to high polarization multiferroics
- 18.Jun.2014 11:30
- PGI Lecture Hall
S.N.Bose National Centre for Basic Sciences, Kolkata
The phenomena of orbital ordering in transition metal oxides has led to certain orbitals being preferentially occupied over other notionally degenerate orbitals. This is driven by orbital polarization effects, but is inevitably accompanied by lattice distortions. As a result, one finds that a particular type of magnetic order is strongly stabilized. In some unusual instances, however, orbital ordering is found to destabilize any type of magnetic order which otherwise seemed likely.
A major issue among multiferroics is that large ferroelectric polarizations are usually seen in systems which have no d electrons. These are associated with distortions which are driven by second order Jahn-Teller effects. The folklore has been that first order Jahn Teller effects, which also result in orbital ordering, lead to symmetric distortions. In this talk I will show how we have designed certain limits where first order Jahn-Teller effects result in orbital ordering, thereby providing us with a route to high polarization multiferroics.
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