Ferromagnetic interlayer coupling in CrSBr crystals irradiated by ions

Layered magnetic materials are becoming a major platform for future spin-based applications. Particularly the air-stable van der Waals compound CrSBr is attracting considerable interest due to its prominent magneto-transport and magneto-optical properties. In this work, we observe a transition from antiferromagnetic to ferromagnetic behavior in CrSBr crystals exposed to high-energy, non-magnetic ions. Already at moderate fluences, ion irradiation induces a remanent magnetization with hysteresis adapting to the easy-axis anisotropy of the pristine magnetic order up to a critical temperature of 110 K. Structure analysis of the irradiated crystals in conjunction with density functional theory calculations suggest that the displacement of constituent atoms due to collisions with ions and the formation of interstitials favors ferromagnetic order between the layers

Efficient Er/O Doped Silicon Photodiodes at Communication Wavelengths by Deep Cooling

Wide band infrared photodetectors have found a wide range of applications in sensing, communication, and spectral analysis. However, the commonly used infrared photodetectors are based on Ge and III‐V semiconductors which are not complementary metal‐oxide‐semiconductor (CMOS) compatible and therefore have limited applications. There is a huge demand for silicon‐based infrared photodetectors due to its low‐cost and compatibility with CMOS processes. Nevertheless, the spectral bandwidth of Si photodetectors is limited to wavelengths below 1.1 µm. Several approaches are developed to extend Si photodetection bandwidth to communication wavelengths. Er/O doped Si is a promising approach which, however, suffers from low infrared responsivities at room temperature when the samples are treated with the standard rapid thermal annealing (RTA). In this work, a novel deep cooling process to treat Er/O doped silicon waveguide photodiodes is applied. In comparison with RTA process, the deep cooling process reduces the defect concentration in silicon by two orders of magnitude, resulting in a two‐orders‐of‐magnitude reduction in leakage current density and an enhanced photoresponsivity to 100 mA W−1 at 1510 nm. The 3dB bandwidth of the silicon waveguide photodiode reaches 30 kHz. The device performance can be further improved by optimizing the deep cooling condition and Er/O doping concentration.Er/O doped Si is a promising approach to realize infrared photodetection. However, it suffers from low infrared responsivities when treated with the standard RTA. In this work, a deep cooling process is applied to treat Er/O doped silicon waveguide photodiodes. Compared with RTA process, the deep cooling process leads to an enhanced photoresponsivity to 100 mA W‐1 at 1510 nm at room temperature.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/168483/1/admt202100137.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/168483/2/admt202100137-sup-0001-SuppMat.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/168483/3/admt202100137_am.pd

Strong Exciton–Phonon Coupling as a Fingerprint of Magnetic Ordering in van der Waals Layered CrSBr

The layered, air-stable van der Waals antiferromagnetic compound CrSBr exhibits pronounced coupling among its optical, electronic, and magnetic properties. As an example, exciton dynamics can be significantly influenced by lattice vibrations through exciton–phonon coupling. Using low-temperature photoluminescence spectroscopy, we demonstrate the effective coupling between excitons and phonons in nanometer-thick CrSBr. By careful analysis, we identify that the satellite peaks predominantly arise from the interaction between the exciton and an optical phonon with a frequency of 118 cm–1 (∼14.6 meV) due to the out-of-plane vibration of Br atoms. Power-dependent and temperature-dependent photoluminescence measurements support exciton–phonon coupling and indicate a coupling between magnetic and optical properties, suggesting the possibility of carrier localization in the material. The presence of strong coupling between the exciton and the lattice may have important implications for the design of light–matter interactions in magnetic semiconductors and provide insights into the exciton dynamics in CrSBr. This highlights the potential for exploiting exciton–phonon coupling to control the optical properties of layered antiferromagnetic materials