Pressure study of magnetism in off-stoichiometric Ni2MnSn-based alloys

•Divergent values of pressure effects on magnetic properties of the off-stoichiometric Ni-Mn-Sn were observed.•Pressure effects confirm recent quantum mechanical calculation of effects of point-defects.•No changes of exchange-spring and exchange-bias effects were detected under pressure. Pressure study of the Heusler Ni2MnSn-based alloys revealed divergent values of the pressure effects on magnetic properties within a group of the off-stoichiometric alloys. An increase in temperature of the structural martensitic transition in the Mn-rich alloys under pressure is adequate for volume changes that accompanied the structural transition. An anomalous decrease of electric resistivity of the alloys in vicinity of the structural transition verifies a transfer into ferromagnetic order of the alloys above the transition temperatures. Almost no changes of exchange-spring and exchange-bias effects were detected under pressure in all the studied alloys. All the observed pressure effects are discussed with help of recent quantum-mechanical calculations of effects of multiple point-defects on magnetism of stoichiometric Ni2MnSn alloy.