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MA: Fachverband Magnetismus

MA 31: Magnetic Particles and Clusters I

MA 31.3: Vortrag

Donnerstag, 26. März 2009, 10:45–11:00, HSZ 401

Influence of stress on the magnetic properties of nanoparticles — •Srinivasa Rao Saranu, Ulf Wiedwald, Sören Selve, Ute Kaiser, Paul Ziemann, and Ulrich Herr — Ulm University,89081 Ulm,Germany

Magnetic nanoparticles are interesting candidates for high density data storage. However, thermal stability of the stored information requires sufficiently large magnetic anisotropy. Here we present a new approach to optimization of the magnetic anisotropy of nanoparticles by applying large persistent stress. Fe and Ni nanoparticles were produced using plasma gas condensation technique and analyzed using XRD, SEM and TEM. Particles were deposited on Ta substrates and in-situ covered with Cu films. The Ta substrate was subsequently loaded with hydrogen. The volume expansion of the substrate induces a biaxial tensile stress in the Cu film. For 40nm Ni particles embedded in Cu films, we find that the effective anisotropy increases linearly with the applied stress. Fe particles with an average diameter of 14nm show super-paramagnetic behavior at room temperature. Upon applying in-plane biaxial stress, the blocking temperature as determined from FC/ZFC cooled magnetization measurements increases significantly.