Strong high-frequency spin waves released periodically from a confined region

Efficient excitation of spin waves is a key issue in magnonics. Here, by using micromagnetic simulation and analytical analysis, we study the excitation of spin waves confined in a limited region by a microwave field with assistance of spin-transfer torque. The results show that the spin-transfer torque can decrease the effective damping constant and increase the spin wave relaxation time substantially. As a result, the amplitude of the excited spin waves is increased greatly. By periodically lifting and establishing the blocking areas, strong spin-wave pulses are released from the confined region. Such generated spin-wave pulses are much stronger than traditionally excited spin waves, especially for high-frequency spin waves. Our study provides a new method to generate strong high-frequency spin waves.