Researchers discover an efficient route towards ultrafast manipulation of magnetism in antiferromagnetic materials

A team of researchers has discovered a mechanism in antiferromagnets that could be useful for spintronic devices. They theoretically and experimentally demonstrated that one of the magnetization torques arising from optically driven excitations has a much stronger influence on spin orientation than previously given credit for. The result of their study could provide a new and efficient mechanism for manipulating spin. which has so far proven to be a challenging task.

Antiferromagnetic materials (AFMs) are good candidates for spintronics because they are resistant to external magnetic fields and allow for switching spin values in timescales of picoseconds. One promising strategy to manipulate spin orientation in AFMs is using an optical laser to create extremely short-lived magnetic field pulses, a phenomenon known as the inverse Faraday effect (IFE). Although the IFE in AFMs generates two very distinct types of torque (rotational force) on their magnetization, it now seems the most important of the two has been somewhat neglected in research.

University of Groningen team takes a step towards analogue spintronic devices

University of Groningen researchers have measured the presence of electron-spin-dependent nonlinearity in a van der Waals heterostructure spintronic device. The team went on to demonstrate its application for basic analog operations such as essential elements of amplitude modulation and frequency sum (heterodyne detection) on pure spin signals, by exploiting the second-harmonic generation of the spin signal due to nonlinear spin injection.

New discovery brings analogue spintronic devices closer imageGraphene (light green) with boron nitride (blue) on top. Measuring points indicated in orange.

The researchers also showed that the presence of nonlinearity in the spin signal has an amplifying effect on the energy-dependent conductivity-induced nonlinear spin-to-charge conversion effect. The interaction of the two spin-dependent nonlinear effects in the spin-transport channel leads to a highly efficient modulation of the spin-to-charge conversion effect, which in principle can also be measured without using a ferromagnetic detector. These effects are measured both at room and low temperatures, and are suitable for their applications as nonlinear circuit elements in the fields of advanced spintronics and spin-based neuromorphic computing.