Electronic and Magnetic Structure of LaSr-2×4 Manganese Oxide Molecular Sieve Nanowires

Abstract

In this study we combine scanning transmission electron microscopy, electron energy loss spectroscopy and electron magnetic circular dichroism to get new insights into the electronic and magnetic structure of LaSr-2×4 manganese oxide molecular sieve nanowires integrated on a silicon substrate. These nanowires exhibit ferromagnetism with strongly enhanced Curie temperature (T c >500 K), and we show that the new crystallographic structure of these LaSr-2×4 nanowires involves spin orbital coupling and a mixed-valence Mn3+/Mn4+, which is a must for ferromagnetic ordering to appear, in line with the standard double exchange explanation.

Applications of STEM-EELS to complex oxides

“…Hence, we carried out a real-space characterization at the sub-nanometer scale of magnetic and electronic properties, via aberration corrected STEM and EELS, which was used to probe the local magnetization of a single nanoparticle at room temperature [67]. Just like macroscopically averaged x-ray magnetic circular dichroism (XMCD), electron magnetic circular dichroism (EMCD) can be measured in transition metal oxides by studying the L 2,3 edges of transition metals while illuminating nanometer-sized specimen areas [72][73][74][75].…”

Hot hole transfer from Ag nanoparticles to multiferroic YMn2O5 nanowires enables superior photocatalytic activity

“…3a. [41][42][43] A shift towards higher energy loss in the composite for all these edges was observed with respect to those of pristine YMn 2 O 5 , which implies strong interaction between them. UV-Vis absorption spectra collected in diffuse reflectance mode (Fig.…”

Integration of functional complex oxide nanomaterials on silicon

“…EMCD measurements performed on a single LaSr-2 × 4 nanowire at room temperature showed that there is a significant orbital component to the magnetic moment and that this is aligned antiparallel to the spin moment [73]. This finding suggests that Mn shells are less than half-filled and that the origin of ferromagnetism may reside in a double-exchange-like mechanism.…”

“…This combination has shown to be a powerful technique for structural, chemical and magnetic analysis down to the atomic scale [73].…”