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Europium titanate has the cubic perovskite structure containing divalent Eu (7 μB) and tetravalent Ti. From magnetic measurements we find that EuTiO3 is one of the few antiferromagnetic materials with a positive θ (TN=5.3°K, θ=3.8°K). At 1.3°K the magnetic moment (σ) increases linearly with field to 10 kOe; above 14 kOe the moment saturates and σ=156 emu/gm (6.93 μB) at 20 kOe. Powder neutron-diffraction work indicates that EuTiO3 has the Type G magnetic structure in which a given Eu++ has six nearest-neighbor europium ions antiparallel and 12 next-nearest-neighbor europium ions parallel. In a perovskite structure where only the 12-coordinated ion is magnetic, i.e., Eu++, the molecular field relations for a two sublattice model yield J1/k=−0.021°K, where J1 is the effective intersublattice exchange interaction, and J2/k=0.040°K, where J2 is the effective intrasublattice exchange interaction. The signs of J1 and J2 are opposite to those found in the europium chalcogenide series. The chalcogenides, however, have the rocksalt structure in which the number of 90° cation-anion-cation interactions differs from the perovskite structure.

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Epitaxial thin films of lanthanum-deficient LaxMnO3−δ (0.67≤x≤1) have been grown on (100) SrTiO3 substrates by pulsed laser deposition. The as-deposited films exhibit a ferromagnetic transition at temperatures ranging from 115 to 240 K, with the transition temperature (Tc) increasing with higher La deficiency. A sharp drop in resistivity and negative magnetoresistance is observed close to Tc, a behavior similar to that observed in divalent substituted La1−xMxMnO3−δ (M=Ba, Sr, Ca, Pb) films. Postannealing the films in O2 reduces the resistivity and raises the Tc to values close to room temperature. A magnetoresistance value of 130% (Δρ/ρH) has been obtained at 300 K at 4 T for a post-annealed film with x=0.75.

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Epitaxial CrO2 thin films have been grown on TiO2(100) and Al2O3(0001) substrates by atmospheric pressure chemical vapor deposition. The films have a Curie temperature (Tc) of around 393 K with the ones grown on TiO2 exhibiting in-plane uniaxial magnetic anisotropy. They also display metallic characteristics, with room temperature resistivity of about 285 μΩ cm, dropping by about two orders of magnitude upon cooling down to 5 K. Magnetoresistance (MR) properties of the films have been measured with the magnetic field in the plane. For a field of 40 kOe, a positive transverse MR of about 25% at 5 K and a negative MR of about 7% at near Tc have been observed. In addition, Hall resistivity has been measured with magnetic field up to 40 kOe. A positive ordinary Hall effect is found at low temperatures, indicating the conduction carriers are holes.

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