Multi-scale simulations of metamagnetic martensite transition in NiCoMnIn

•We developed a multi-scale model to investigate metamagnetic transitions.•We used first principle calculation to indentify transition temperature.•The transition temperature can be tuned by the external stimulus.•Martensite variant boundaries are superposed with 90° magnetic domain walls.

A multi-scale theoretical model is performed to investigate magnetic field-induced metamagnetic martensite transition in NiCoMnIn alloys. First, the total energy is calculated to demonstrate antiferromagnetic-ferromagnetic transition from first principle calculation. Second, the transition temperature from antiferromagnetic to ferromagnetic can be tuned by the external magnetic field and hydrostatic pressure in thermodynamic calculation, which is consistent with experimental results. Third, phase field simulation found that martensite variant boundaries are superposed with the 90° antiferromagnetic magnetic domain walls, revealing magneto-structural coupling between structural and magnetic domain structures. It is demonstrated that this multi-scale model is very effective for describing antiferromagnetic-ferromagnetic accompanied with martensite-austenite transitions with magnetostructural coupling.