Ferromagnetism at the surface of a LaCoO3 single crystal observed using scanning SQUID microscopy

Evidence for ferromagnetism at the surface of a LaCo O3 single crystal is reported using a scanning superconducting quantum interference device (SQUID) microscope. Stray magnetic flux detected with the scanning SQUID shows typical ferromagnetic behavior in LaCo O3 below Tc ∼85 K, in agreement with previous work on LaCo O3 particles. Analysis of the magnetization of LaCo O3 particle samples clearly shows that the magnetization is inversely proportional to the particle radius, giving the information that the ferromagnetism is restricted within a few unit cell layers from the surface. X-ray photoemission spectroscopy also indicates that the ferromagnetism likely originates from the metallic surface due to hole doping with oxygen chemisorption

Weak Ferromagnetism in LaCo1-xRhxO3: Anomalous Magnetism Emerging between Two Nonmagnetic End Phases

Magnetization has been measured for polycrystalline samples of LaCo1-xRhxO3 (0 {\leq} x {\leq} 0.9) in order to investigate magnetism induced in the solid solution of two nonmagnetic end phases of LaCoO3 and LaRhO3. It is found that a ferromagnetic transition is observed below 15 K in the range of x from 0.1 to 0.4. The effective Bohr magnetic moment evaluated from the temperature dependence of magnetic susceptibility at around room temperature is independent of x for 0 < x < 0.5 (approximately 3 {\mu}B per formula unit), and rapidly decreases above x = 0.5. On the basis of detailed magnetization measurements, the spin state and magnetic ordering of LaCo1-xRhxO3 are discussed.Comment: 16 pages, 6 figures, to be published in J. Phys. Soc. Jp

Photoinduced Phase Transition in Pr 0.5

A perovskite-type cobalt oxide, $Pr_{0.5}Ca_{0.5}CoO_3$ (PCCO), shows photoinduced phase transition. In this study, we successively irradiated two laser pulses with different intensities to PCCO and probed the transient change of the reflection at 2.0 eV. Assuming propagation of the two different photoinduced metallic states, we could reproduce the time profiles as well as the magnitude in the reflectance change, indicating the fabrication of the photoinduced multilayered thin film in $Pr_{0.5}Ca_{0.5}CoO_3$

Photoinduced Phase Transition in Pr0.5Ca0.5CoO3Pr_{0.5}Ca_{0.5}CoO_3 Studied by Sequential Pulse Excitations

A perovskite-type cobalt oxide, $Pr_{0.5}Ca_{0.5}CoO_3$ (PCCO), shows photoinduced phase transition. In this study, we successively irradiated two laser pulses with different intensities to PCCO and probed the transient change of the reflection at 2.0 eV. Assuming propagation of the two different photoinduced metallic states, we could reproduce the time profiles as well as the magnitude in the reflectance change, indicating the fabrication of the photoinduced multilayered thin film in $Pr_{0.5}Ca_{0.5}CoO_3$