A first order structural Jahn-Teller transition at T_{JT} = 650 K has been recently reported for the quadruple perovskite LaMn7O12 . We have carried out magnetization and transport measurements below and above T_{JT} in order to investigate the effect of the transition. Electrical conduction turns out to be polaronic, changing from non-adiabatic to adiabatic through the transition. Magnetic behavior can be described by non-interacting Mn3+ ions below T_{JT}, while above T_{JT} it is of questionable interpretation. The effect of thermal cycling on as grown samples of different purity degree also allowed us to clarify the intrinsic magnetic response of LaMn7O12 at lower temperatures.
@article{arxiv.0905.1500,
title = {The high temperature Jahn-Teller transition in LaMn7O12},
author = {R. Cabassi and F. Bolzoni and E. Gilioli and F. Bissoli and A. Prodi and A. Gauzzi},
journal= {arXiv preprint arXiv:0905.1500},
year = {2009}
}