Purely Antiferromagnetic Magnetoelectric Random Access Memory

TL;DR

This paper introduces a purely antiferromagnetic magnetoelectric RAM that significantly reduces writing energy, is robust against disturbances, and enables all-electric readout at room temperature, advancing antiferromagnetic spintronics.

Contribution

The authors demonstrate a novel AF-MERAM device using Cr2O3, achieving a 50-fold reduction in writing threshold and providing a comprehensive model of the magnetoelectric switching mechanism.

Findings

50-fold reduction in writing threshold compared to ferromagnetic RAM

Reliable isothermal switching via gate voltage pulses at room temperature

Identification of growth-induced ferrimagnetism affecting robustness

Abstract

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 to 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 of these novel systems, we construct a comprehensive model of the magnetoelectric selection mechanism in thin films of magnetoelectric antiferromagnets. We identify that growth induced effects lead to emergent ferrimagnetism, which is detrimental to the robustness of the storage. After pinpointing lattice misfit as the likely origin, we provide routes to enhance or mitigate this emergent ferrimagnetism as desired. Beyond memory applications, the AF-MERAM concept introduces a general all-electric interface for antiferromagnets and should find wide applicability in purely antiferromagnetic spintronics devices.