Defined magnetization states in magnetic nanotubes could be the basic building blocks for future memory elements. To date, it has been extremely challenging to measure the magnetic states at the single-nanotube level. We investigate the magnetization states of an individual Ni nanotube by measuring the anisotropic magnetoresistance effect at cryogenic temperature. Depending on the magnitude and direction of the magnetic field, we program the nanotube to be in a vortex-or onion-like state near remanence.

Recent experimental and theoretical work has focused on ferromagnetic nanotubes due to their potential applications as magnetic sensors or as elements in high-density magnetic memory. The possible presence of magnetic vortex statesstates which produce no stray fields makes these structures particularly promising as storage devices. Here we investigate the behavior of the magnetization states in individual Ni nanotubes by sensitive cantilever magnetometry. Magnetometry measurements are carried out in the three major orientations, revealing the presence of different stable magnetic states. The observed behavior is well-described by a model based on the presence of uniform states at high applied magnetic fields and a circumferential onion state at low applied fields.

Using an optimally coupled nanometer-scale SQUID, we measure the magnetic flux originating from an individual ferromagnetic Ni nanotube attached to a Si cantilever. At the same time, we detect the nanotube's volume magnetization using torque magnetometry. We observe both the predicted reversible and irreversible reversal processes. A detailed comparison with micromagnetic simulations suggests that vortexlike states are formed in different segments of the individual nanotube. Such stray-field free states are interesting for memory applications and noninvasive sensing.

Spin wave propagation in a magnetron-sputtered CoFeB thin film is investigated. We apply both in-plane and out-of-plane magnetic fields. At room temperature, we find velocities of up to 25 and 3.5 km/s, respectively. These values are much larger compared to a thin permalloy film. Analyzing the resonance linewidth, we obtain an intrinsic Gilbert damping parameter of about 0.007 at room temperature. It increases to 0.023 at 5 K. CoFeB is a promising material for magnonic devices supporting fast propagating spin waves. V C 2012 American Institute of Physics.

High quality YBazCu307 thin films can be grown by reactive thermal co-evaporation. Combined with a rotating disk heater this method allows to fabricate even double sided homogeneous films on substrate areas up to 9" diameter. A scanning inductive jc probe is used to monitor the homogeneity of critical current densities of typically >2 MA/cm2. Surface resistance values are found to be below 500 63 10 GHz. On biaxially aligned buffer layers on polycrystalline substrates jc values of 1.3 MA/cmz are achieved as well. The properties of Ndl.,Baz+,Cu307 films grown with the same system are presented and evaluated.