First crystal growth and magnetic structure of the high-temperature antiferromagnet Cr2Al

Switching Néel vector orientations in antiferromagnets has been proposed as an ultrafast means of data storage, but the fundamental energy scales of switching cannot be evaluated without oriented measurements on single crystals. These single-crystal methods are vital for understanding if first-principles calculations can predict the energies and dynamics that govern these devices.

The leading antiferromagnetic spintronic material Mn2Au cannot be “switched off” by heating above its Néel temperature T_N, so probing its magnetic energy experimentally is challenging. We grew the first single crystals of Cr₂Al to show that it has the same magnetic configuration as Mn₂Au (at left, orange arrows), but Cr₂Al transitions to a paramagnet at TN = 634 K. Neutron diffraction revealed that the magnetic ordering is in-plane. Divergence of the magnetic susceptibility χ_v along a and c directions is clear at T_N (right, in black and red). Our Monte Carlo simulations match the experimental T_N, shown by the peak in calculated heat capacity (C_v at right, in blue).