Sub-GHz Frequency Response of Anomalous Nernst Effect in the NiFe Block with Sinusoidal Laser Pulses

Abstract

Because the anomalous Nernst effect (ANE) involves the effective electric field generated by the combination between the thermal gradient and the magnetization direction, it has been well applied to not only the measurement of the static magnetization but also the experiment for the low frequency magnetization dynamics. In this work, the frequency response of the ANE was examined to provide two implications: First, as a method to separate Nernst effects from other signals in the homodyne or heterodyne method, and second, as a timing reference to the phase-sensitive magnetization dynamics. The intensity of 1550 nm laser power was modulated up to 2.4 GHz and successfully produced the equivalent speed of the ANE signals from the 10 nm Permalloy block on the sapphire substrate. The implications could be supported, when the detection system consists of well-designed radio frequency components and the better heat sink substrate to get the faster thermal gradient on the magnets.