Probing Magnetic Properties of Photoexcited CrSBr Using Electron Spin Resonance

The potential applications of two-dimensional (2D) magnets in magnetoelectric, magneto-optic, and spintronic devices have accelerated research into low-dimensional magnetism, driven by their promise for energy-efficient quantum technologies and topological quantum computing. Attributed to its distinctive properties (1, 2), CrSBr is a promising material in the fields of spintronics, quantum computing, and sensing. It offers stable magnetism and tunable electronic properties with A-type antiferromagnetic order (T_N = 132 K). In this work, we investigated the magnetic, magnetic resonance properties of CrSBr upon photoexcitation at 520 nm and 800nm as a function of temperature. We employed electron paramagnetic resonance (EPR) and Vibrating Sample Magnetometry (VSM) to explore the potential for tuning magnetic interactions. We found distinct signatures both at continuous wave and time resolved EPR spectra. At room temperature, CrSBr showed maximum intensity at 520 nm and intensity decreased with increasing wavelength (decreasing irradiation energy). Temperature dependent magnetization lowered by 24 emu/g (40%) in photon exited (800nm) sample compared to pristine. Photoexcitation at 800nm resulted in an about 7K increase of T_N. Furthermore, in time-resolved spectra at 140 K with 280 nm excitation, the spectral profile exhibits a shift and becomes narrower. These changes indicate the tunability of magnetic interactions. Our research highlights the pivotal role of photon irradiation in modulating the magnetic properties and interactions of 2D van der Waals magnets.