title: Magnetic properties of rare-earth-doped La0.7Sr0.3MnO3.
abstract: Rare-earth-doped ferromagnetic manganites La0.63RE0.07Sr0.30MnO3(RE  =  Gd, Tb, Dy, and Ho) are synthesized in the form of sintered ceramics and nanocrystalline phases with the mean size of crystallites  ≈30 nm. The electronic states of the dopants are investigated by SQUID magnetometry and theoretically interpreted based on the calculations of the crystal field splitting of rare-earth energy levels. The samples show the orthorhombic perovskite structure of Ibmm symmetry, with a complete FM order of Mn spins in bulk and reduced order in nanoparticles. Non-zero moments are also detected at the perovskite A sites, which can be attributed to magnetic polarization of the rare-earth dopants. The measurements in external field up to 70 kOe show a standard Curie-type contribution of the spin-only moments of Gd3+ions, whereas Kramers ions Dy3+and non-Kramers ions Ho3+contribute by Ising moments due to their doublet ground states. The behaviour of non-Kramers ions Tb3+is anomalous, pointing to singlet ground state with giant Van Vleck paramagnetism. The Tb3+doping leads also to a notably increased coercivity compared to other La0.63RE0.07Sr0.30MnO3systems.
authors.affiliation: Institute of Physics, ASCR, Cukrovarnická 10/112, 162 00 Prague 6, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Veverka
authors.forename: Ondřej
authors.initials: O
authors.lastname: Kaman
authors.forename: Karel
authors.initials: K
authors.lastname: Knížek
authors.forename: Pavel
authors.initials: P
authors.lastname: Novák
authors.forename: Miroslav
authors.initials: M
authors.lastname: Maryško
authors.forename: Zdeněk
authors.initials: Z
authors.lastname: Jirák