Direct Imaging of Temperature-Dependent Layered Antiferromagnetism of a Magnetic Oxide

Abstract

With the use of a newly developed spin-polarized scanning electron microscope, we have succeeded in obtaining the real-space images of the layered-antiferromagnetic state concurrent with 1-nm-stepped atomic terraces in layered-structure manganite La1.4Sr1.6Mn2O7. The three-dimensional analysis of spin alignment could further reveal the temperature-dependent spin reorientation and the anfiferromagnetic domain walls on the atomic terraces. These ensure the use of the present microscopy for quantitative analysis of local magnetic structures in a broader range of materials, including magnetic oxides and nanomaterials.

Observation of Magnetic Ripple and Nanowidth Domains in a Layered Ferromagnet

“…Such a stripe-domain structure has a periodic wavy structure in the magnetization direction, which is caused by the competition between the magnetostatic and the magnetocrystalline anisotoropic energies. However, according to our LTEM observation, the For x 0:30 and 0.32, as increasing temperature, the SRTs from the c axis towards the ab plane were reported [14,16,24,25]. We show in Fig.…”

“…Arrows on the right of the respective crystal structures represent the magnetic moment of Mn within a single MnO 2 layer unit. not only the cleaved ab face but also the ac face, which is of great advantage over spin-polarized scanning electron microscopy [16]. Besides, the phase separation has been observed between the ferromagnetic phase and the antiferromangetic charge-ordered one in manganites on nanometer to micrometer scale by the LTEM technique [17][18][19].…”

Spin-Polarized Scanning Electron Microscopy (Spin SEM) and its recent progress

“…The probing depth of spin SEM is reported to be shorter than 1 nm 11) , and it has been successfully applied to observe the magnetic domain structures in layered -antiferromagnetism of perovskite materials. 15) So one would be expected to measure the magnetization of the grain-boundary phase of a NdFeB sintered magnet by preparing the fractured surface in spin SEM chamber of UHV condition. First, we established the method to observe magnetic domain structures on a fractured surface of NdFeB sintered magnet by spin SEM, as shown in Fig.6.…”

“…Previously, we have demonstrated the characteristics of spin SEM by showing the measurements of magnetic devices such as magnetic recording tapes 12) , HDD devices 13) and permanent magnet 14) , besides those in fundamental physics at low temperatures. 15) Since then, spin SEM has further improved its functions and kept trying novel measurement methods; therefore it is still gathering much attentions. In this article, the recent results of spin SEM measurements are introduced, after the brief summary of the principle and the characteristic of spin SEM.…”

Magnetic domain structure of La0.7Sr0.3MnO3 thin-films probed at variable temperature with scanning electron microscopy with polarization analysis

“…Furthermore it allows one to probe the spin polarization of the material by measuring the contrast provided by the secondary electron spin polarization. Previous work has applied the technique to bulk crystals of LSMO and related oxides 13,14 but imaging of the technologically relevant thin films has been lacking. Additionally, for a full understanding it is necessary to image as a function of temperature, down to cryogenic conditions, since changes in the films properties have been seen 15 .…”