Conference Presentation (Invited)

FZJ-2020-01041

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Tuning the structural and magnetic properties of transition metal oxide nanoparticles

SUN, X. ; DIPPEL, A.-C. ; ULLRICH, A. ; PETRACIC, O.FZJ* ; BRÜCKEL, T.FZJ*

2020

Abstract: Magnetic nanoparticles (NPs) have attracted interests in both fundamental research and industry. We focus on two transition metal oxide systems: manganese oxide and iron oxide. The structural information of the particles was characterized using X-ray powder diffraction, total scattering experiments with pair distribution function analysis, small angle scattering as well as scanning electron microscopy. The magnetic properties were studied using a SQUID magnetometer. In the hysteresis loops of the as-prepared NPs an exchange bias effect is found. By comparing hysteresis loops cooled at different magnetic fields, a hardening effect is observed, i.e. the squareness and hardness of hysteresis loops is significantly enhanced with increasing magnetic cooling field. By varying the oxygen content inside the NPs via different annealing procedures, their crystallographic structures change. The bonding lengths as well as the correlation lengths of different phases in the particles are obtained using total scattering with pair distribution function analysis. The relationship between the correlation lengths and the exchange bias as well as the magnetic hardening effects is elucidated.

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Contributing Institute(s):

1. Streumethoden (JCNS-2)
2. Streumethoden (PGI-4)
3. JARA-FIT (JARA-FIT)

Research Program(s):

1. 144 - Controlling Collective States (POF3-144) (POF3-144)
2. 524 - Controlling Collective States (POF3-524) (POF3-524)
3. 6212 - Quantum Condensed Matter: Magnetism, Superconductivity (POF3-621) (POF3-621)
4. 6213 - Materials and Processes for Energy and Transport Technologies (POF3-621) (POF3-621)
5. 6G4 - Jülich Centre for Neutron Research (JCNS) (POF3-623) (POF3-623)

Appears in the scientific report 2020

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