Effects of Selective Dilution on the MagneticProperties of La0.7Sr0.3Mn1-xM'xO3 (M' = Al, Ti)

Abstract

The magnetic lattice of mixed-valence Mn ions in La0.7Sr0.3MnO3 is selectively diluted by partial substitution of Al or Ti for Mn. The ferromagnetic transition temperature Tc and the saturation magnetization Ms both decrease with substitution. By presenting the data in terms of selective dilution, Tc in the low-doping region is found to follow the relation Tc = Tc0(1−np), where Tc0 refers to the undiluted system and np is the dilution concentration defined as np = x/0.7 or np = x/0.3 for M ′ = Al or Ti, respectively. The scaling behavior of Tc(np) can be analyzed in the framework of the molecular-field theory and still valid when Mn is substituted by both Al and Ti. The results are discussed with respect to the contributions from ferromagnetic double exchange and other possible antiferromagnetic superexchange interactions coexisting in the material.

Interfacial Ion Intermixing Effect on Four-Resistance States in La0.7Sr0.3MnO3/BaTiO3/La0.7Sr0.3MnO3 Multiferroic Tunnel Junctions

“…This behavior should be related to the asymmetric intermixing at the interfaces. The intermixing at the interfaces is analogous to the Ti 4+ substitution for Mn 4+ in LSMO, , and increases the ratio of Mn 3+ /Mn 4+ and breaks the MnOMn network, as reflected in the local chemical state changes at the interfaces. The double exchange coupling between Mn 3+ and Mn 4+ in the La 0.7 Sr 0.3 MnO 3 layer adjacent to the interfaces will be obviously weakened, , and the resistivity of the LSMO layer adjacent to the interfaces will be greatly increased.…”

“…The intermixing at the interfaces is analogous to the Ti 4+ substitution for Mn 4+ in LSMO, , and increases the ratio of Mn 3+ /Mn 4+ and breaks the MnOMn network, as reflected in the local chemical state changes at the interfaces. The double exchange coupling between Mn 3+ and Mn 4+ in the La 0.7 Sr 0.3 MnO 3 layer adjacent to the interfaces will be obviously weakened, , and the resistivity of the LSMO layer adjacent to the interfaces will be greatly increased. It is clearly revealed that the intermixing and the local chemical state changes at the bottom interface is much more obvious than that at the top interface, which will result in the double exchange coupling between Mn 3+ and Mn 4+ at bottom interface being much more sensitive to ferroelectric field-induced doping than that at top interface.…”

Magnetic properties and Griffiths singularity in La0.45Sr0.55 Mn1−xCoxO3

“…This not only changes the bandwidth and the hole concentration, but also introduces a Mn-site disorder into the system. The substitution with metal elements for the Mn ions generally suppresses the ferromagnetism [8][9][10][11][12][13]. However, different from these general ionic substitutions, Co doping in LaMnO 3 yields a peculiar effect and attracts more attention.…”