Non-volatile high-temperature shell-magnetic pinning of Ni-Mn-Sn Heusler precipitates obtained by decomposition under magnetic field

Highlights: • Shell-magnetic pinning of Heusler precipitates are embedded in an antiferromagnetic NiMn matrix. • The pinning causes vertical shifts in hysteresis loops. • The remanences on increasing and decreasing field are both positive. The thermodynamic instability of the off-stoichiometric Ni_49.8Mn_45.1Sn_5.1 martensitic Heusler causes it to decompose into ferromagnetic Ni₅₀Mn₂₅Sn₂₅ precipitates and an antiferromagnetic NiMn matrix. If the decomposition takes place under an applied magnetic field, the shell of the precipitates acquires a preferred spin orientation that is strongly pinned by the anisotropy of the matrix. The pinning leads to a large vertical shift in the field dependence of the magnetization even at temperatures as high as 500 K. The positive remanence remains permanent even when the magnetic field is cycled or when the sample is directionally manipulated with respect to the external field, providing a non-volatile magnetic-field-proof memory as a further functionality to those existing in martensitic Heuslers.