Посилання:Magnetic and transport properties controlled by structural disorder in La₀.₇Ca₀.₃MnO₃ films / V.G. Prokhorov, V.A. Komashko, G.G. Kaminsky, V.L. Svetchnikov, Y.P. Lee, S.Y. Park // Физика низких температур. — 2004. — Т. 30, № 9. — С. 938–944. — Бібліогр.: 21 назв. — англ.
Підтримка:This work was supported by the KOSEF through
the Quantum Photonic Science Research Center.
The magnetic properties of an amorphous, a partially-disordered, and a lattice-strained crystalline
La₀.₇Ca₀.₃MnO₃ film are investigated. It is shown that the amorphous film exhibits Curie-
Weiss-type paramagnetism with the effective magnetic moment of 4.2 µB/Mn ion and a small
ferromagnetic contribution governed by the formation of a quasi-two-dimensional crystalline interfacial
inclusions. The crystalline film with nanocrystalline randomly-oriented inclusions demonstrates
a superposition of ferromagnetic (in the crystalline matrix) and superparamagnetic (in the
inclusions) nature. The fitted average size of the superparamagnetic particles in the case of a
Langevin function is coincident with that of the nanocrystalline clusters reveated in high-resolution
electron-microscopy images. An increase in the applied magnetic field leads to a reduction in
the average magnetic moment of superparamagnetic particles, which is due to an enhancement of
the ferromagnetic coupling between the individual randomly-oriented crystallites. The completely
crystalline film undergoes only a ferromagnetic transition with a saturation magnetization at 5 K
of 2.73 µB /Mn ion.