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 TN, 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 χv along a and c directions is clear at TN (right, in black and red). Our Monte Carlo simulations match the experimental TN, shown by the peak in calculated heat capacity (Cv at right, in blue).