Examinando por Autor "Berja, Alba"

Mostrando 1 - 2 de 2

Restringido
Asymmetric magnetic response induced by compositional gradients in Ni-Fe nanowires
(IEEE Nanotechnology Council (NTC), 2024-07-09) Fernández González, Claudia; Gómez Cruz, Lucía; Álvaro Gómez, Laura; Berja, Alba; Martín-Rubio, Carolina; Waqas Khaliq, M.; Foerster, Michael; Niño, M. Ángel; Mascaraque, Arantzazu; Sanz, Ruy; Aballe, Lucía; Pérez, Lucas; Ruiz Gómez, Sandra
"The control over the domain wall motion in cylindrical nanostructures is a key factor for developing the next generation of spintronic and logic devices [1,2]. Among several strategies, introducing changes in the chemical structure of the wire (chemical barriers) has been proved to be an effective way to pin the domain walls [3], but determining the direction of the domain wall movement still remains as an open challenge. Following the same approach, in this work we introduced gradients of composition in Ni-Fe nanowires to pattern a ratchet profile of the domain wall energy along the nanowire axis, in order to create an asymmetry for the domain wall movement. Nanowires were synthesized using template assisted electrodeposition. Composition was gradually changed between Ni90Fe10 to Ni35Fe65 along the nanowire longitudinal axis in periods of a few micrometres (fig.1.a). Combining laterally resolved X-ray Absorption Spectro-microscopy (XAS) and X-ray Magnetic Circular Dichroism (XMCD) we correlate the chemical structure of single nanowires with their 3D spin texture. By applying external magnetic fields along the nanowire axis, we studied the evolution of the magnetic state depending on the field direction. In addition, First Order Reversal Curves (FORC) were also measured in arrays of nanowires. The FORC diagrams of nanowires with homogeneous composition and nanowires with axial gradients of composition are shown in fig.1.b-c. While the diagram of homogeneous nanowires is highly symmetric with respect to the interaction field axis (HU)(b), an asymmetry arises in the diagram of nanowires with axial gradients (red square) (c), evidencing the emerging of asymmetrical magnetization processes in the nanowires [4]."
Acceso Abierto
Asymmetrical magnetization processes induced by compositional gradients in ferromagnetic nanowires
(Elsevier, 2024-01-16) Fernández González, Claudia; Berja, Alba; Álvaro Gómez, Laura; Martín-Rubio, Carolina; Mascaraque, Arantzazu; Aballe, Lucía; Sanz, Ruy; Pérez, L.; Ruiz Gómez, Sandra; Centros de Excelencia Severo Ochoa, INSTITUTO MADRILEÑO DE ESTUDIOS AVANZADOS EN NANOCIENCIA, SEV-2016-0686
Electrodeposited nanowires are an excellent scenario to study and control magnetic domain wall motion in nanostructures. In particular, the introduction of local changes in composition during the growth procedure has been proven to be very efficient for controlling the magnetization dynamics. In this work, we show the possibility of introducing compositional gradients in FeNi electrodeposited nanowires by gradually changing the Fe/Ni ratio along their axis. These compositional gradients produce an asymmetrical landscape for domain wall motion which is reflected in asymmetrical magnetization processes under an applied magnetic field. By studying nanowires with different compositional gradients we were able to correlate composition and magnetic asymmetry. Our results pave the way towards full control of the movement of domain walls along the nanowires.