All-Electric Access to the Magnetic-Field-Invariant Magnetization of Antiferromagnets.

The rich physics of thin film antiferromagnets can be harnessed for prospective spintronic devices given that all-electric assessment of the tiny uncompensated magnetic moment is achieved. On the example of magnetoelectric antiferromagnetic Cr2O3, we prove that spinning-current anomalous Hall magnetometry serves as an all-electric method to probe the field-invariant uncompensated magnetization of antiferromagnets. We obtain direct access to the surface magnetization of magnetoelectric antiferromagnets providing a read-out method for ferromagnet-free magnetoelectric memory. Owing to the great sensitivity, the technique bears a strong potential to address the physics of antiferromagnets. Exemplarily, we apply the method to access the criticality of the magnetic transition for an antiferromagnetic thin film. We reveal the presence of field-invariant uncompensated magnetization even in 6-nm-thin IrMn films and clearly distinguish two contributions, of which only the minor one is involved in interfacial magnetic coupling. This approach is likely to advance the fundamental understanding of the anomalous Hall and magnetic proximity effects.

Purely antiferromagnetic magnetoelectric random access memory.

Magnetic random access memory schemes employing magnetoelectric coupling to write binary information promise outstanding energy efficiency. We propose and demonstrate a purely antiferromagnetic magnetoelectric random access memory (AF-MERAM) that offers a remarkable 50-fold reduction of the writing threshold compared with ferromagnet-based counterparts, is robust against magnetic disturbances and exhibits no ferromagnetic hysteresis losses. Using the magnetoelectric antiferromagnet Cr2O3, we demonstrate reliable isothermal switching via gate voltage pulses and all-electric readout at room temperature. As no ferromagnetic component is present in the system, the writing magnetic field does not need to be pulsed for readout, allowing permanent magnets to be used. Based on our prototypes, we construct a comprehensive model of the magnetoelectric selection mechanisms in thin films of magnetoelectric antiferromagnets, revealing misfit induced ferrimagnetism as an important factor. Beyond memory applications, the AF-MERAM concept introduces a general all-electric interface for antiferromagnets and should find wide applicability in antiferromagnetic spintronics.