Universität zu Köln

Zakutna, Dominika ORCID: 0000-0001-9417-6514, Niznansky, Daniel, Barnsley, Lester C., Babcock, Earl, Salhi, Zahir, Feoktystov, Artem, Honecker, Dirk ORCID: 0000-0003-0763-982X and Disch, Sabrina ORCID: 0000-0002-4565-189X (2020). Field Dependence of Magnetic Disorder in Nanoparticles. Phys. Rev. X, 10 (3). COLLEGE PK: AMER PHYSICAL SOC. ISSN 2160-3308

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Abstract

The performance characteristics of magnetic nanoparticles toward application, e.g., in medicine and imaging or as sensors, are directly determined by their magnetization relaxation and total magnetic moment. In the commonly assumed picture, nanoparticles have a constant overall magnetic moment originating from the magnetization of the single-domain particle core surrounded by a surface region hosting spin disorder. In contrast, this work demonstrates the significant increase of the magnetic moment of ferrite nanoparticles with an applied magnetic field. At low magnetic field, the homogeneously magnetized particle core initially coincides in size with the structurally coherent grain of 12.8(2) nm diameter, indicating a strong coupling between magnetic and structural disorder. Applied magnetic fields gradually polarize the uncorrelated, disordered surface spins, resulting in a magnetic volume more than 20% larger than the structurally coherent core. The intraparticle magnetic disorder energy increases sharply toward the defect-rich surface as established by the field dependence of the magnetization distribution. In consequence, these findings illustrate how the nanoparticle magnetization overcomes structural surface disorder. This new concept of intraparticle magnetization is deployable to other magnetic nanoparticle systems, where the in-depth knowledge of spin disorder and associated magnetic anisotropies are decisive for a rational nanomaterials design.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Zakutna, Dominika UNSPECIFIED orcid.org/0000-0001-9417-6514 UNSPECIFIED Niznansky, Daniel UNSPECIFIED UNSPECIFIED UNSPECIFIED Barnsley, Lester C. UNSPECIFIED UNSPECIFIED UNSPECIFIED Babcock, Earl UNSPECIFIED UNSPECIFIED UNSPECIFIED Salhi, Zahir UNSPECIFIED UNSPECIFIED UNSPECIFIED Feoktystov, Artem UNSPECIFIED UNSPECIFIED UNSPECIFIED Honecker, Dirk UNSPECIFIED orcid.org/0000-0003-0763-982X UNSPECIFIED Disch, Sabrina UNSPECIFIED orcid.org/0000-0002-4565-189X UNSPECIFIED
URN:	urn:nbn:de:hbz:38-325759
DOI:	10.1103/PhysRevX.10.031019
Journal or Publication Title:	Phys. Rev. X
Volume:	10
Number:	3
Date:	2020
Publisher:	AMER PHYSICAL SOC
Place of Publication:	COLLEGE PK
ISSN:	2160-3308
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Chemistry > Institute of Physical Chemistry
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language FERRITE NANOPARTICLES; SIZE DISTRIBUTION; COBALT FERRITE; SPIN DISORDER; SURFACE; PHASE; ANISOTROPY; DIFFRACTION; RESONANCE; MOMENT Multiple languages Physics, Multidisciplinary Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/32575