Michael Street

Dielectric breakdown along c-axis boundaries in magnetoelectric O2O3 for spintronic devices

Voltage controlled boundary magnetism is crucial for spintronic devices with reduced power consumption. Magnetoelectric and antiferromagnetic Cr2O3 is an ideal material due to its electric field switching of nonvolatile boundary magnetism [1]. The boundary magnetization can switch an adjacent soft ferromagnetic layer via voltage-controlled exchange bias. Bulk Cr2O3 has a high dielectric breakdown field of 1000 KVmm and a large bandgap of 3.4 eV. However, even with a small electrode size of 0.04 mm and thick Cr2O3 film of 0.5 μm, the highest reported dielectric breakdown field of Cr2O3 films is only 200 KVmm [2]. The breakdown field drops rapidly to 8 KVmm if electrode size increases to 35 mm and film thickness decreases to 250 nm [2], making electric field induced switching of Cr2O3 based heterostructures very difficult. Here, we combine aberration corrected STEM characterization and spin polarized density functional theory (DFT) calculations to elucidate the structure, electronic properties, and magnetic properties of a new type of interface-stabilized planar crystallographic defect in Cr2O3 thin films that explains the structural origin of dielectric breakdown.