Imaging Neel Vector Switching Using Nitrogen Vacancy Centers in Diamond

Control of the orientation of the antiferromagnetic order parameter in systems with multiple easy-axes is provides a promising route to high frequency information processing.  NV relaxometry arising from the resulting terahertz magnetic dynamics could provide diagnostic imaging. Nitrogen vacancy (NV) centers are sensitive, local and non-invasive probes of magnetic dynamics but have until recently been limited to detection of dynamics at or below the NV resonant frequency (~3 GHz). It has recently been shown that two magnons in ferromagnetic and antiferromagnetic systems may scatter emitting electromagnetic noise at their difference frequency. Thus THz frequency dynamics associated antiferromagnetic magnons, which would otherwise be undetectable using an NV, can be detected when this difference frequency is resonant with the NV precession. Switching the Neel vector from one easy-axis to another can be achieved by means of current-induced spin-orbit torque.