Impact of partial strain on the magnetic properties of thin films
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Answer:
The functional perovskite La1−xSrxMnO3 (LSMO) possesses various exotic phases owing to competing physical parameters and internal degrees of freedom. In particular, the nature of the ferromagnetic insulating phase (FMI) has not been adequately explored, resulting in a limited understanding of the relationship between crystal structure and magnetism. To investigate this structure–property relationship, epitaxial La0.88Sr0.12MnO3 thin films were grown on two different substrates, (001) SrTiO3 and (001) (LaAlO3)0.3(Sr2AlTaO6)0.7, by pulsed laser deposition. Element-specific and surface-sensitive techniques were applied in conjunction with bulk magnetometry to investigate the inextricable link between the structures and magnetic properties of the films and the effects of tuning the strain. The results unambiguously demonstrate that structure–property relationship of a FMI LSMO tuned by strain has a crucial role for manipulating the properties in the FMI regime.
Answer:
Bulk EuTiO3 is known as a compound in which spin and soft phonon mode is strongly coupled. Recent theoretical study suggests that application of stress or formation of strain leads to a drastic change in magnetic and dielectric properties of EuTiO3 and that so-called multiferroic properties emerge under such a situation. In the present study, effect of strain induced by a substrate, on which EuTiO3 thin film is deposited, on the magnetic properties of the film has been experimentally examined. By using a pulsed laser deposition method, EuTiO3 thin film has been deposited on different kinds of substrate, i.e., LaAlO3, SrTiO3, and DyScO3; the lattice parameter of these compounds is smaller than, just the same as, and larger than that of EuTiO3, respectively. X-ray diffraction analysis confirms that the strain induced in the plane of as-deposited EuTiO3 thin films on different substrates is coincident with the lattice parameter of the substrate compounds. Also, all the as-deposited EuTiO3 thin films manifest elongation of lattice in a direction perpendicular to the film surface. Temperature dependence of magnetization indicates that all the thin films exhibit ferromagnetic behavior at low temperatures. The magnetization at 2 K under a magnetic field of 100 Oe is the highest for EuTiO3 on DyScO3 and the lowest for EuTiO3 on LaAlO3. The experimental result is coincident with the first-principles calculations which predict that ferromagnetic spin configuration becomes more stable as the lattice volume of EuTiO3is increased.