A route to high polarization multiferroics

Large ferroelectric polarizations are usually seen in d0 ferroelectrics, while those with a finite d-electron count usually have a polarization which is two orders of magnitude smaller. The route then to high polarization multiferroics, seems quite obvious - examine if we can stabilize the d0 type distortions in ?nite d-electron systems. The way we went about this was to dope carriers into BaTiO3 and examine if ferroelectricity survived. Considering the example of V doping in BaTiO31, we found that ferroelectricity was strongly stabilized, much stronger that in the undoped limit. Microscopic modeling coupled with ab-initio calculations revealed that part of the stability of the ferroelectric distortions about the V site emerged from orbital ordering. The dilute doping limit was used to identify some guiding principles and helped us design new multiferroics2,3. Surpisingly, this also forced us to reexamine the microscopic origin of ferroelectricity and provided new insights4. 1. H. Chandra, K. Gupta, A. Nandy and P. Mahadevan, Phys. Rev B. (in press). 2. K. Gupta, H. Chandra and P. Mahadevan (submitted). 3. K. Gupta, P. Mahadevan, P. Mavropoulus and M. Lezaic (submitted). 4. A. Kumar, H. Chandra and P. Mahadevan (submitted).