DOE OSTI · 3022068
Metallicity and anomalous Hall effect in epitaxially strained, atomically thin RuO 2 films
Abstract
The anomalous Hall effect (AHE), a hallmark of time-reversal symmetry breaking, has been reported in rutile RuO 2 , a debated metallic altermagnetic candidate. Previously, AHE in RuO 2 was observed only in strain-relaxed thick films under extremely high magnetic fields (~50 T). Yet, in ultrathin strained films with distinctive anisotropic electronic structures, there are no reports, likely due to disorder and defects suppressing metallicity thus hindering its detection. Here, we demonstrate that ultrathin, fully strained 2 nm TiO 2 /t nm RuO 2 /TiO 2 (110) heterostructures, grown by hybrid molecular beam epitaxy, retain metallicity and exhibit a sizeable AHE at a significantly lower magnetic field (< 9 T). Density functional theory calculations reveal that epitaxial strain stabilizes a noncompensated magnetic ground state and reconfigures magnetic ordering in RuO 2 (110) thin films. These findings establish ultrathin RuO 2 as a platform for strain-engineered magnetism and underscore the transformative potential of epitaxial design in advancing spintronic technologies.
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Jeong, Seung Gyo [University of Minnesota−Twin Cities, Minneapolis, MN (United States)] (ORCID:0000000225043571), Lee, Seungjun [University of Minnesota−Twin Cities, Minneapolis, MN (United States)] (ORCID:0000000181971287), Lin, Bonnie [Massachusetts Institute of Technology, Cambridge, MA (United States)], Yang, Zhifei [University of Minnesota−Twin Cities, Minneapolis, MN (United States)], Choi, In Hyeok [Gwangju Institute of Science and Technology (Korea, Republic of)], Oh, Jin Young [Sungkyunkwan University, Suwon (Korea, Republic of)], Song, Sehwan [Pusan National University, Busan (Korea, Republic of)], Lee, Seung wook [Gwangju Institute of Science and Technology (Korea, Republic of)], Nair, Sreejith [University of Minnesota−Twin Cities, Minneapolis, MN (United States)], Choudhary, Rashmi [University of Minnesota−Twin Cities, Minneapolis, MN (United States)] (ORCID:0000000235581277), Parikh, Juhi [University of Minnesota−Twin Cities, Minneapolis, MN (United States)] (ORCID:000000022345668X), Park, Sungkyun [Pusan National University, Busan (Korea, Republic of)], Choi, Woo Seok [Sungkyunkwan University, Suwon (Korea, Republic of)] (ORCID:0000000228726191), Lee, Jong Seok [Gwangju Institute of Science and Technology (Korea, Republic of)], LeBeau, James M. [Massachusetts Institute of Technology, Cambridge, MA (United States)], Low, Tony [University of Minnesota−Twin Cities, Minneapolis, MN (United States)], Jalan, Bharat [University of Minnesota−Twin Cities, Minneapolis, MN (United States)] (ORCID:0000000279400490). 2025-06-11. Metallicity and anomalous Hall effect in epitaxially strained, atomically thin RuO 2 films. https://doi.org/10.1073/pnas.2500831122
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