Role of spin-transfer torques on synchronization and resonance phenomena in stochastic magnetic oscillators

• Autor(a) principal: Accioly, Artur Difini
• Data de Publicação: 2016
• Outros Autores: Locatelli, Nicolas, Mizrahi, Alice, Querlioz, Damien, Pereira, Luis Gustavo, Grollier, Julie, Kim, Joo-Von
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRGS
• Texto Completo: http://hdl.handle.net/10183/169430
• topic: Sistemas estocásticos; Osciladores; Torque; Superparamagnetismo; Dinâmica de spin; Tunelamento magnético

A theoretical study on how synchronization and resonance-like phenomena in superparamagnetic tunnel junctions can be driven by spin-transfer torques is presented. We examine the magnetization of a superparamagnetic free layer that reverses randomly between two well-defined orientations due to thermal fluctuations, acting as a stochastic oscillator. When subject to an external ac forcing, this system can present stochastic resonance and noise-enhanced synchronization. We focus on the roles of the mutually perpendicular damping-like and field-like torques, showing that the response of the system is very different at low and high frequencies. We also demonstrate that the field-like torque can increase the efficiency of the current-driven forcing, especially at sub-threshold electric currents. These results can be useful for possible low-power, more energy efficient applications.