Prediction of multiferroicity in the layered hydrogen-bonded system α-CrOOH: Proton transfer ferroelectricity and strain-tunable magnetic transition

•First-principles calculations plus Monte Carlo simulations are used to investigate the multiferroicity of α-CrOOH.•α-CrOOH with a robust FE and AFM near room temperature.•a tiny tensile strain can transform α-CrOOH from AFM ground state to FM.•Ti2CO2/α-CrOOH/ Ti2CO2H FE FETs can be used for various applications such as high-density NVM. Ferroelectric materials with vertical polarization could provide ground-breaking device applications, compatible with electric-field switching even in the presence of a surface-depolarizing field. Herein, we present theoretical evidence that rhombohedral chromium oxide hydroxide α-CrOOH, which has been synthesized experimentally, is a type-Ⅰ multiferroic. First-principles calculations plus Monte Carlo simulations indicate that α-CrOOH is a room temperature proton transfer ferroelectricity semiconductor with robust electric polarization as large as 24.6 μC/cm2. Moreover, the system exhibits an anti-ferromagnetism ground state with a Neel temperature of 340 K, where strain can modulate the transition from antiferromagnetic to ferromagnetic. Finally, a two-dimensional (2D) heterostructure model was designed, composed of monolayer α-CrOOH and functional MXene, for various applications such as non-volatile memory (NVM). The remarkable properties may enable the system to hold great potential for the development of future multifunctional devices.