Ni₂MnAl single crystals for magnetic scattering neutron holography

Ni₂MnAl phase has the B2 crystal structure when an alloy was prepared at the moderate cooling rate. However, the crystal structure of Ni ₂MnAl oders from the B2 structure to the L2₁ structure by annealing at lower temperature than approximately 773 K. Ni₂MnAl with the L2₁ structure exhibits martensitic phase transformation and ferromagnetic phase transition with decreasing temperature. On the contrary, Ni₂MnAl with high Al content with the B2 structure exhibit no martensitic transformation but antiferromagnetic transition. With further cooling, Ni₂MnAl with the B2 structure exhibit transition from antiferromagnetic phase to spin glass phase. Ni₂MnAl with the B2 structure is suitable for developing a method to measure spin state of solids.