High-Frequency Dynamics Modulated by Collective Magnetization Reversal in Artificial Spin Ice

Spin-torque ferromagnetic resonance arises in heavy metal-ferromagnet heterostructures when an alternating charge current is passed through the bilayer stack. The methodology to detect the resonance is based on the anisotropic magnetoresistance, which is the change in the electrical resistance due to different orientations of the magnetization. In connected networks of ferromagnetic nanowires, known as artificial spin ice, the magnetoresistance is rather complex owing to the underlying collective behavior of the geometrically frustrated magnetic domain structure. Here, we demonstrate spin-torque ferromagnetic resonance investigations in a square artificial spin-ice system and correlate our observations to magneto-transport measurements. The experimental findings are described using a simulation approach that highlights the importance of the correlated dynamics response of the magnetic system. Here, our results open the possibility of designing reconfigurable microwave oscillators and magnetoresistive devices based on connected networks of nanomagnets.