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arXiv · 2309.12493

Post deposition interfacial N\'eel temperature tuning in magnetoelectric B:Cr2O3

Ather Mahmood·Jamie Weaver·Syed Qamar Abbas Shah·Will Echtenkamp·Jeffrey W. Lynn·Peter A. Dowben·Christian Binek
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Abstract

Boron (B) alloying transforms the magnetoelectric antiferromagnet Cr2O3 into a multifunctional single-phase material which enables electric field driven {\pi}/2 rotation of the N\'eel vector. Nonvolatile, voltage-controlled N\'eel vector rotation is a much-desired material property in the context of antiferromagnetic spintronics enabling ultra-low power, ultra-fast, nonvolatile memory, and logic device applications. N\'eel 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 environments, the N\'eel 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. We attribute the B-enrichment to surface segregation. Magnetotransport data confirm B-accumulation at the interface within a layer of about 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 N\'eel vector rotation at 370 K performed over the course of weeks.

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Ather Mahmood, Jamie Weaver, Syed Qamar Abbas Shah, Will Echtenkamp, Jeffrey W. Lynn, Peter A. Dowben, Christian Binek. 2023-09-21. Post deposition interfacial N\'eel temperature tuning in magnetoelectric B:Cr2O3. https://doi.org/10.1002/apxr.202300061

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