Multilsegmented nanostructures

 

Multisegmented nanostructures are expected to be particularly useful in the field of catalysis, advanced microfluidics, molecule separation, and biological and magnetic sensors. It is worth mentioning that multisegmented magnetic nanostructures consisting of regular arrays of magnetic segments have been considered as providing the basis for extending magnetic storage densities beyond the superparamagnetic limit. In such a system, a single structure with n magnetic layers might store up to 2n bits, with a volume much larger than those of the grains in conventional recording media, beating this way thermal fluctuations and increasing the recording density by a factor 2n−1 [1].

 

Recently, we have demonstrated that the use of multilayer nanotubes can help to stabilize magnetic nanoparticles inside ferromagnetic nanotubes, where the parallel alignment of segments seems to be less effective in trapping the particle since only the field landscape created by antiparallel aligned magnetization in the segments is capable of restraining the particleʼs domain wall movement [2,3]. Besides, we have found that when a magnetic field is applied parallel to the axis of a cylindrical nanostructure with wire–tube morphology [4], different reversal modes can be induced in each section by choosing the right geometrical parameters and a step or plateau appears on the hysteresis curve, corresponding to a partial pinning of the domain wall at the interface between wire and tube sections. Finally, we have performed micromagnetic simulations to investigate the angular dependence of the magnetic properties of these cylindrical nanostructures with wire–tube morphology [5,6].

 

[1] J. Escrig, P. Landeros, D. Altbir, M. Bahiana, J. d'Albuquerque e Castro, Magnetic properties of layered nanorings, Applied Physics Letters 89, 132501 (2006).

[2] R. F. Neumann, M. Bahiana, J. Escrig, S. Allende, K. Nielsch, D. Altbir, Stability of magnetic nanoparticles inside ferromagnetic nanotubes, Applied Physics Letters 98, 022502 (2011).

[3] R. F. Neumann, M. Bahiana, S. Allende, J. Escrig, D. Altbir, Confinement of magnetic nanoparticles inside multisegmented nanotubes by means of magnetic field gradients, Journal of Applied Physics 111, 013916 (2012).

[4] D. Salazar-Aravena, R. M. Corona, D. Goerlitz, K. Nielsch, J. Escrig, Magnetic properties of multisegmented cylindrical nanoparticles with alternating magnetic wire and tube segments, Journal of Magnetism and Magnetic Materials 346, 171-174 (2013).

[5] D. Salazar-Aravena, J. L. Palma, J. Escrig, Angular dependence of the magnetic properties of cylindrical nanostructures with wire-tube morphology, Materials Research Express 1, 026112 (2014).

[6] Muhammad Shahid Arshad, Darja Pecko, Saso Sturm, Juan Escrig, Matej Komelj, Paul J. McGuiness, Spomenka Kobe, K. Zuzek Rozman, Angular dependence of the coercivity in electrodeposited Co-Pt nanostructures with a tube-wire morphology, IEEE Transactions on Magnetics 50, 2302904 (2014).