Affiliation:
1. Department of Physics & Astronomy and the Nebraska Center for Materials and Nanoscience University of Nebraska‐Lincoln Lincoln NE 68588‐0299 USA
2. Material Measurement Laboratory National Institute of Standards and Technology Gaithersburg MD 20899 USA
3. Department of Electrical & Computer Engineering University of Minnesota Minneapolis MN 55455 USA
4. NIST Center for Neutron Research National Institute of Standards and Technology Gaithersburg MD 20899 USA
Abstract
AbstractBoron (B) alloying transforms the magnetoelectric antiferromagnet Cr2O3 into a multifunctional single‐phase material which enables electric field driven π/2 rotation of the Néel vector. Nonvolatile, voltage‐controlled Néel vector rotation is a much‐desired material property in the context of antiferromagnetic spintronics enabling ultralow power, ultrafast, nonvolatile memory, and logic device applications. Néel vector rotation is detected with the help of heavy metal (Pt) Hall‐bars in proximity of pulsed laser deposited B:Cr2O3 films. To facilitate operation of B:Cr2O3‐based devices in CMOS (compementary metal‐oxide semiconductor) environments, the Néel temperature, TN, of the functional film must be tunable to values significantly above room temperature. Cold neutron depth profiling and X‐ray photoemission spectroscopy depth profiling reveal thermally activated B‐accumulation at the B:Cr2O3/ vacuum interface in thin films deposited on Al2O3 substrates. The B‐enrichment is attributed to surface segregation. Magnetotransport data confirm B‐accumulation at the interface within a layer of ≈50 nm thick where the device properties reside. Here TN enhances from 334 K prior to annealing, to 477 K after annealing for several hours. Scaling analysis determines TN as a function of the annealing temperature. Stability of post‐annealing device properties is evident from reproducible Néel vector rotation at 370 K performed over the course of weeks.
Funder
National Science Foundation
National Institute of Standards and Technology