Fig. 1: Simultaneous imaging of amplitude and phase of AC magnetic fields up to MHz frequencies.
From: Imaging AC magnetization response of soft magnetic thin films using diamond quantum sensors
a Illustration of the measurement principle and frequency range coverage. Qurack protocol was employed up to 200 kHz, utilizing microwave (MW) frequency modulation. The amplitude and phase of frequency modulation were varied to explore the matching condition. In the MHz range, Qdyne protocol was utilized, where the AC magnetic field was undersampled by MW pulses synchronized to the AC field, allowing camera frame rates to capture the oscillations. The undersampled waveform facilitated the determination of the original waveform’s amplitude and phase. The operational frequency limits for Qdyne are defined by the 1/T2 decay and the speed of Rabi oscillations. b Raw data from a 10-kHz Qurack measurement. The vertical and horizontal axes show the amplitude and phase of the MW frequency modulation, respectively. The color map represents the photoluminescence (PL) accumulated over 10 ms. A dip in PL indicates the matching condition. c Raw data from a 2.3 MHz Qdyne measurement. Here, the 2.3 MHz AC magnetic field is undersampled to a 2.1 Hz waveform.
