Zhiyong Quan, Biao Wu, Fei Zhang, Guowei Zhou, Julu Zang, Xiaohong Xu.
Room temperature insulating ferromagnetism induced by charge transferin ultrathin (110) La0.7Sr0.3MnO3 films.
(Appl. Phys. Lett., 2017, 110, 072405 )
Abstract
The achievement of high
temperature
ferromagnetism
in perovskite manganites has proved both fundamentally and technologically important for spintronics devices. However, high operating
temperatures
have not been achieved due to the depression of the Curie
temperature
and the rapid spin filtering efficiency loss, which are the main obstacles for practical applications. Here, we report unexpected room
temperature
insulating
ferromagnetism
in ultrathin (110) oriented La0.7Sr0.3MnO3 (LSMO)
films.
The relationships between room
temperature
ferromagnetism,
charge transfer,
and orbital occupancy are investigated, with
X-ray absorption spectroscopy
(XAS)
and
X-ray
linear dichroism (XLD)
measurements.
Our results suggest that the room
temperature
insulating
ferromagnetism
is originated from super-exchange interaction between Mn2+ and Mn3+. The formation of Mn2+ions is related to the
charge transfer
induced by oxygen
vacancies.
Moreover, a preferential orbital occupancy of eg(3z2-r2) in Mn3+ ions is crucial to the in-plane super-exchange coupling in ultrathin (110) LSMO
films,
resulting in insulating
ferromagnetic
behavior. This work may lead to the development of barrier
materials
in spin filter tunnel junctions and understanding of
ferromagnetic
coupling in insulating perovskite
films.
全文链接： https://aip.scitation.org/doi/10.1063/1.4976699
