Metal-insulator transition above room temperature in maximum colossal magnetoresistance manganite thin films

It has been suggested that the maximum magnitude of colossal magnetoresistance occurs in mixed-valent manganites with a tolerance factor $t=0.96$ [Zhou, Archibald, and Goodenough, Nature (London) 381, 770 (1996)]. However, at t≈0.96 most manganites have relatively low values of the metal-insulator transition temperature TMI0.3em0ex(~60--1500.3em0exK). Here, we report that a 50 {} La0.9Sr0.1MnO₃ thin film with $t=0.96$ grown on a (100) SrTiO₃ substrate has a metal-insulator transition above room temperature, which represents a doubling of TMI compared with its value in the bulk material. We show that this spectacular increase of TMI is a result of the epitaxially compressive strain-induced reduction of the Jahn-Teller distortion.