Study of the interfaces between magnetic thin films and antiferromagnetic substrates by synchrotron radiation photoelectron emission microscopy

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Photoemission Electron Microscope (PEEM) equipment operated at our laboratory in the Photon Factory beamline, Tsukuba, is used for the magnetic domain imaging. Combining the merits with the circular and linear magnetic dichroism effects and tunability of the photon energy, we can obtain the element specific domain images both for ferro-and antiferromagnetic materials. This advantage allows us to get the information not only for thin films but also for substrates and interfaces. However, in order to use this advantage completely, samples should be rotated freely and precisely in plane and for a variety of temperature. We designed a new sample manipulator for this purpose.During the period of this project, we mainly perform the experiments at the beamline BL11A, 13C and 2C of the Photon Factory. The substrate was NiO(100). Cr or Fe thin film was deposited onto the substarate. For the Cr/NiO(100) system, we found the modulation contrast of the NiO antifferomagnetic domain as a function of … More Cr thickness. This may originates from the exchange coupling between the Cr and Ni magnetic moments. In odd monolayer thickness regions of Cr, the NiO magnetic domain contrast decreases whereas the contrast remains in even layer regions. It is supposed that the net magnetization exists in odd layer Cr region and no magnetization in even layer regions. Therefore, only at the odd layer region, the contrast may be suppressed. For Fe?NiO(100) system, we found out very complicated domain structures in Fe thin film as a function of the thickness. This also originates from the exchange coupling between the film and the substrate, but further, we should consider the domain structures caused by the anisotropy energy of film itself. We further found out the T-donain (originating from twin structure due to antiferromagnetic crystal distortion) is not affected by the film deposition whereas the S-domain (originating from spin structure) is strongly affected. This phenomenon is distinguished by the comparative observation of domains at Ni-L edge and O-K edge.We also perform the experiment at the beamlines at SPring-8 (BL-23 SU, 25SU and 27SU), where the higher performance PEEMs are installed than at the PF. We clearly distinguished the T-and S-domains of NiO. We further succeeded to observe detailed X-ray absorption spectra with richer features than those reported previously. This success was done by the microscopic measurements from the non-damaged surface area of NiO. Less