Moiré-assisted charge instability in ultrathin RuO$_2$

Fuente: arXiv
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Autori principali: Keßler, Philipp, Feuerpfeil, Andreas, Consiglio, Armando, Hohmann, Hendrik, Thomale, Ronny, Erhardt, Jonas, Liu, Bing, Jovic, Vedran, Claessen, Ralph, Härtl, Patrick, Dürrnagel, Matteo, Moser, Simon
Natura: Preprint
Pubblicazione: 2025
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author Keßler, Philipp
Feuerpfeil, Andreas
Consiglio, Armando
Hohmann, Hendrik
Thomale, Ronny
Erhardt, Jonas
Liu, Bing
Jovic, Vedran
Claessen, Ralph
Härtl, Patrick
Dürrnagel, Matteo
Moser, Simon
author_facet Keßler, Philipp
Feuerpfeil, Andreas
Consiglio, Armando
Hohmann, Hendrik
Thomale, Ronny
Erhardt, Jonas
Liu, Bing
Jovic, Vedran
Claessen, Ralph
Härtl, Patrick
Dürrnagel, Matteo
Moser, Simon
contents Ruthenium dioxide (RuO$_2$) has been in the focus of contemporary condensed matter research as a prototypical candidate material for altermagnetism. In the face of daunting evidence for bulk magnetic order despite promising theoretical predictions, it naturally suggests the focus on thin films where Coulomb interactions are dimensionally quenched and may yield a more strongly correlated environment prone to magnetic ordering. Here, we combine scanning tunneling microscopy (STM), density functional theory (DFT), and density matrix renormalization group (DMRG) methods to investigate atomically ordered ultrathin RuO$_2$(110) grown on Ru(0001). Contrary to predictions of magnetic order, we observe a nonmagnetic charge density wave (CDW) instability that is driven by Fermi surface nesting within the flat-band surface state, and stabilized by the incommensurate moiré stacking with the substrate. We further identify a nonmagnetic and metastable 2 $\times$ 2 surface reconstruction that breaks in-plane mirror symmetry and can be reversibly toggled via STM tip manipulation. Our spin-polarized STM measurements find no sign of any magnetic instability at the RuO$_2$ surface. As much as our findings refute proposals for either bulk or surface magnetism in RuO$_2$, we establish ultrathin RuO$_2$(110) as an intriguing platform for exploring Moiré-assisted electronic surface order.
format Preprint
id arxiv_https___arxiv_org_abs_2507_05047
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Moiré-assisted charge instability in ultrathin RuO$_2$
Keßler, Philipp
Feuerpfeil, Andreas
Consiglio, Armando
Hohmann, Hendrik
Thomale, Ronny
Erhardt, Jonas
Liu, Bing
Jovic, Vedran
Claessen, Ralph
Härtl, Patrick
Dürrnagel, Matteo
Moser, Simon
Materials Science
Strongly Correlated Electrons
Ruthenium dioxide (RuO$_2$) has been in the focus of contemporary condensed matter research as a prototypical candidate material for altermagnetism. In the face of daunting evidence for bulk magnetic order despite promising theoretical predictions, it naturally suggests the focus on thin films where Coulomb interactions are dimensionally quenched and may yield a more strongly correlated environment prone to magnetic ordering. Here, we combine scanning tunneling microscopy (STM), density functional theory (DFT), and density matrix renormalization group (DMRG) methods to investigate atomically ordered ultrathin RuO$_2$(110) grown on Ru(0001). Contrary to predictions of magnetic order, we observe a nonmagnetic charge density wave (CDW) instability that is driven by Fermi surface nesting within the flat-band surface state, and stabilized by the incommensurate moiré stacking with the substrate. We further identify a nonmagnetic and metastable 2 $\times$ 2 surface reconstruction that breaks in-plane mirror symmetry and can be reversibly toggled via STM tip manipulation. Our spin-polarized STM measurements find no sign of any magnetic instability at the RuO$_2$ surface. As much as our findings refute proposals for either bulk or surface magnetism in RuO$_2$, we establish ultrathin RuO$_2$(110) as an intriguing platform for exploring Moiré-assisted electronic surface order.
title Moiré-assisted charge instability in ultrathin RuO$_2$
topic Materials Science
Strongly Correlated Electrons
url https://arxiv.org/abs/2507.05047