Banca de QUALIFICAÇÃO: FARNÉSIO VIEIRA DA SILVA DINIZ

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : FARNÉSIO VIEIRA DA SILVA DINIZ
DATA : 28/01/2022
HORA: 14:00
LOCAL: Sala virtual
TÍTULO:

Domain wall excitations by spin polarized current

PALAVRAS-CHAVES:

Domain wall excitations, spin polarized current, nano-oscillators

PÁGINAS: 50
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Física
SUBÁREA: Física da Matéria Condensada
ESPECIALIDADE: Materiais Magnéticos e Propriedades Magnéticas
RESUMO:

Since the discovery of the spin-transfer torque (STT) effect by Slonczewski and Berger, tremendous and continuous interest has been aroused in the study of current-driven spin dynamics in confined magnetic structures due to the fundamental physics involved and the prospect for technological applications. In a confined magnetic structure such as a nanowire as a proper direct current is passed through, the transfer of spin angular momentum from conduction electron to local spins drives a persistent precession of local spins in the free layer or an oscillation of a pinned domain wall in a nanowire. The magnetization oscillations in magnetic nanostructures due to the current-driven domain wall (DW) oscillation open a new method for the generation of microwave oscillations. The magnetic nanostructures can be utilized to build nano-scale oscillators with the tunable frequency in the microwave range, which has important applications in various areas such as wireless communication. So far, one kind of current-driven magnetic nano-oscillators is the domain wall-based nano-oscillator (DWNO). The most studied DWNO is based on a magnetic nanowire with pinning notches. Here, we will investigate the domain wall-based nano-oscillator in a bilayer consisting of a flat rectangular ferromagnetic wire exchange coupled to a two-sublattices vicinal antiferromagnetic (AF) substrate fulfills the main requirements for constructing a periodic sequence of pinned domain walls. A vicinal two-sublattices AF substrate is a high Miller indexes stacking which may be tailored to consist of a periodic repetition of terraces composed of spins of opposite AF sublattices, separated by steps perpendicular to the direction of the AF spins. This may lead to a corresponding arrangement in the ferromagnetic film, which may turn structured with alternating domains separated by head-to-head and tail-to-tail in-plane domain walls centered at the step’s edges. As expected, since the restoring force is associated with the strength of the interface exchange field, our preliminary results show that the frequency of the domain wall oscillation is a function of the interface exchange field and the geometrical parameters. However, in this study, we will investigate the frequency of a domain wall sequence oscillation. We will analyze the effects of the dipolar interaction and chiralities on the oscillations of a sequence of magnetic domain wall.

MEMBROS DA BANCA:
Externo ao Programa - 12216 - LEONARDO LINHARES OLIVEIRA
Externa ao Programa - 12268 - MARIA DAS GRAÇAS DIAS DA SILVA
Externo à Instituição - GUSTAVO DE OLIVEIRA GURGEL REBOUÇAS - UFERSA