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We present a comparative, theoretical study of the doping dependence of the critical temperature $T_C$ of the ferromagnetic insulator-metal transition in Gd-doped and O-deficient EuO, respectively. The strong $T_C$ enhancement in Eu$_{1-x}$Gd$_x$O is due to Kondo-like spin fluctuations on the Gd sites, which are absent in EuO$_{1-x}$. Moreover, we find that the $T_C$ saturation in Eu$_{1-x}$Gd$_x$O for large $x$ is due to a reduced activation of dopant electrons into the conduction band, in agreement with experiments, rather than antiferromagnetic long-range contributions of the RKKY interaction. The results shed light on possibilities for further increasing $T_C$.
We report on an enhancement of the Curie temperature in GaMnAs/InGaMnAs superlattices grown by low-temperature molecular beam epitaxy, which is due to thin InGaMnAs or InGaAs films embedded into the GaMnAs layers. The pronounced increase of the Curie
A series of polycrystalline pyrochlore rare-earth titanate Ho_{2-x}Cr_xTi_2O_7 are synthesized in order to enhance the ferroelectricity of pyrochlore Ho2Ti2O7. For the sample close to the doping level x=0.4, a giant enhancement of polarization P up t
When comparing a set of La0.67Sr0.33MnO3 (LSMO) samples, the Curie temperature (TC) of the samples is an important figure of merit for the sample quality. Therefore, a reliable method to determine TC is required. Here, a method based on the analysis of the magnetization loops is proposed.
We report on tunneling magnetoresistance (TMR) experiments that demonstrate the existence of a significant spin polarization in Co-doped (La,Sr)TiO3-d (Co-LSTO), a ferromagnetic diluted magnetic oxide system (DMOS) with high Curie temperature. These
We show for the system La1-xCexCoO3 (0.1 <= x <= 0.4) that it is possible to synthesize electron-doped cobaltites by the growth of epitaxial thin films. For La1-xCexCoO3, ferromagnetic order is observed within the entire doping range (with the maximu