The crystal structure, vibrational spectra, and magnetic structure of the quasi-two-dimensional layered van der Waals antiferromagnet CrSBr were studied by means of x-ray diffraction (XRD) and Raman spectroscopy at high pressures up to 33 GPa and ambient temperature and neutron diffraction (ND) up to 5.7 GPa in the temperature range 10–300 K. The orthorhombic crystal structure with Pmmn symmetry observed at ambient pressure remains stable at pressures up to 8 GPa according to the XRD and Raman data. At ambient pressure, $A$-type antiferromagnetic (AFM) order is formed in the initial orthorhombic phase below $T_{\mathrm{N}}=133\mathrm{K}$. Application of high pressure leads to a suppression of the $A$-type AFM order. The Néel temperature decreases sharply by 30% to 93 K, and Cr ordered magnetic moment values are reduced from $3.1{\mu }_{\mathrm{B}}$ to $2.0{\mu }_{\mathrm{B}}$ in the pressure range 0–5.7 GPa, as found in the ND experiments. The effects of pressure-controlled compressive intralayer biaxial lattice strain and interlayer uniaxial lattice strain along the $c$ axis on the magnetic state of CrSBr are analyzed. The evaluated relationship between the variation of the biaxial lattice strain and observed modification of the $T_{\mathrm{N}}$ value via the tuning of structural parameters points to its important role in the tuning of magnetic properties. Upon further compression, a complex sequence of structural phase transitions at $P_1\sim 8, P_2\sim 16$, and $P_3\sim 28\mathrm{GPa}$ was detected by the XRD and Raman measurements. The first possible phase transition at $P_1\sim 8\mathrm{GPa}$ is accompanied by anomalies in the pressure behavior of lattice parameters and softening of the lowest-frequency vibrational mode with $A_{\mathrm{g}}$ symmetry. The second phase transition at $P_2\sim 16\mathrm{GPa}$ is associated with the appearance of the ($\frac{1}{2}01$) superstructure peak in the XRD spectra and extra modes in Raman spectra, pointing to the formation of a structural modification with the supercell doubled along the $a$ axis. The third phase transition at $P_3\sim 28\mathrm{GPa}$ is accompanied by the disappearance of the superstructure peak in the XRD spectra, implying a breakdown of the supercell back to the initial cell geometry. All the observed phases of CrSBr demonstrate pseudo-orthorhombic character, and they are structurally similar, according to the XRD data. The possible appearance of a subtle monoclinic distortion in the high-pressure phases cannot be excluded due to the observation of extra Raman modes above the $P_2$ and $P_3$ transition pressures. The present experimental information is important for further clarification of possible microscopic mechanisms for controlling the magnetic states of CrSBr and relevant van der Waals materials through the application of high external pressures or strain engineering.

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• Magnetic order
• Phase transitions
• Pressure effects
• Structural properties
• Antiferromagnets
• Layered crystals
• Neutron diffraction
• Raman spectroscopy
• X-ray diffraction