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DOE OSTI · 3022077

Strain-stabilized interfacial polarization tunes work function over 1 eV in RuO 2 /TiO 2 heterostructures

Jeong, Seung Gyo [University of Minnesota−Twin Cities, Minneapolis, MN (United States)] (ORCID:0000000225043571)·Lin, Bonnie Y. X. [Massachusetts Institute of Technology, Cambridge, MA (United States)]·Jin, Mengru [Texas A&M University, College Station, TX (United States)] (ORCID:0000000229259572)·Choi, In Hyeok [Gwangju Institute of Science and Technology (GIST) (Korea, Republic of)]·Lee, Seungjun [University of Minnesota, Minneapolis, MN (United States)] (ORCID:0000000181971287)·Yang, Zhifei [University of Minnesota−Twin Cities, Minneapolis, MN (United States); University of Minnesota, Minneapolis, MN (United States)]·Nair, Sreejith [University of Minnesota−Twin Cities, Minneapolis, MN (United States)] (ORCID:0000000244572698)·Choudhary, Rashmi [University of Minnesota−Twin Cities, Minneapolis, MN (United States)]·Parikh, Juhi [University of Minnesota−Twin Cities, Minneapolis, MN (United States)]·Santhosh, Anand [University of Minnesota−Twin Cities, Minneapolis, MN (United States)]·Neurock, Matthew [University of Minnesota−Twin Cities, Minneapolis, MN (United States)]·Stoerzinger, Kelsey A. [University of Minnesota−Twin Cities, Minneapolis, MN (United States)] (ORCID:0000000234318290)·Lee, Jong Seok [Gwangju Institute of Science and Technology (GIST) (Korea, Republic of)] (ORCID:0000000163177944)·Low, Tony [University of Minnesota, Minneapolis, MN (United States)] (ORCID:0000000257595899)·Tu, Qing [Texas A&M University, College Station, TX (United States)]·LeBeau, James M. [Massachusetts Institute of Technology, Cambridge, MA (United States)] (ORCID:0000000277263533)·Jalan, Bharat [University of Minnesota−Twin Cities, Minneapolis, MN (United States)] (ORCID:0000000279400490)
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Abstract

Interfacial polarization – charge accumulation at the heterointerface – is a well-established tool in semiconductors, but its influence in metals remains unexplored. Here, we demonstrate that interfacial polarization can robustly modulate surface work function in metallic rutile RuO 2 layers in epitaxial RuO 2 /TiO 2 heterostructures grown by hybrid molecular beam epitaxy. Using multislice electron ptychography, we directly visualize polar displacements of transition metal ions relative to oxygen octahedra near the interface, despite the conductive nature of RuO 2 . This interfacial polarization enables over 1 eV modulation of the RuO 2 work function, controlled by small thickness variations (2-3 nm), as measured by Kelvin probe force microscopy, with a critical thickness of ~4 nm – corresponding to the transition from fully-strained to relaxed film. These results establish interfacial polarization as a powerful route to control electronic properties in metals and have implications for designing tunable electronic, catalytic, and quantum devices through interfacial control in polar metallic systems.

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Jeong, Seung Gyo [University of Minnesota−Twin Cities, Minneapolis, MN (United States)] (ORCID:0000000225043571), Lin, Bonnie Y. X. [Massachusetts Institute of Technology, Cambridge, MA (United States)], Jin, Mengru [Texas A&M University, College Station, TX (United States)] (ORCID:0000000229259572), Choi, In Hyeok [Gwangju Institute of Science and Technology (GIST) (Korea, Republic of)], Lee, Seungjun [University of Minnesota, Minneapolis, MN (United States)] (ORCID:0000000181971287), Yang, Zhifei [University of Minnesota−Twin Cities, Minneapolis, MN (United States); University of Minnesota, Minneapolis, MN (United States)], Nair, Sreejith [University of Minnesota−Twin Cities, Minneapolis, MN (United States)] (ORCID:0000000244572698), Choudhary, Rashmi [University of Minnesota−Twin Cities, Minneapolis, MN (United States)], Parikh, Juhi [University of Minnesota−Twin Cities, Minneapolis, MN (United States)], Santhosh, Anand [University of Minnesota−Twin Cities, Minneapolis, MN (United States)], Neurock, Matthew [University of Minnesota−Twin Cities, Minneapolis, MN (United States)], Stoerzinger, Kelsey A. [University of Minnesota−Twin Cities, Minneapolis, MN (United States)] (ORCID:0000000234318290), Lee, Jong Seok [Gwangju Institute of Science and Technology (GIST) (Korea, Republic of)] (ORCID:0000000163177944), Low, Tony [University of Minnesota, Minneapolis, MN (United States)] (ORCID:0000000257595899), Tu, Qing [Texas A&M University, College Station, TX (United States)], LeBeau, James M. [Massachusetts Institute of Technology, Cambridge, MA (United States)] (ORCID:0000000277263533), Jalan, Bharat [University of Minnesota−Twin Cities, Minneapolis, MN (United States)] (ORCID:0000000279400490). 2026-02-09. Strain-stabilized interfacial polarization tunes work function over 1 eV in RuO 2 /TiO 2 heterostructures. https://doi.org/10.1038/s41467-026-69200-x

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