Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Superconductivity without insulating states in twisted bilayer graphene
  stabilized by monolayer WSe$_2$   Magic-angle twisted bilayer graphene (TBG), with rotational misalignment
close to 1.1$^\circ$, features isolated flat electronic bands that host a rich
phase diagram of correlated insulating, superconducting, ferromagnetic, and
topological phases. The origins of the correlated insulators and
superconductivity, and the interplay between them, are particularly elusive.
Both states have been previously observed only for angles within $\pm0.1^\circ$
from the magic-angle value and occur in adjacent or overlapping electron
density ranges; nevertheless, it is still unclear how the two states are
related. Beyond the twist angle and strain, the dependence of the TBG phase
diagram on the alignment and thickness of insulating hexagonal boron nitride
(hBN) used to encapsulate the graphene sheets indicates the importance of the
microscopic dielectric environment. Here we show that adding an insulating
tungsten-diselenide (WSe$_2$) monolayer between hBN and TBG stabilizes
superconductivity at twist angles much smaller than the established magic-angle
value. For the smallest angle of $\theta$ = 0.79$^\circ$, we still observe
clear superconducting signatures, despite the complete absence of the
correlated insulating states and vanishing gaps between the dispersive and flat
bands. These observations demonstrate that, even though electron correlations
may be important, superconductivity in TBG can exist even when TBG exhibits
metallic behaviour across the whole range of electron density.
Finite-magnetic-field measurements further reveal breaking of the four-fold
spin-valley symmetry in the system, consistent with large spin-orbit coupling
induced in TBG via proximity to WSe$_2$. Our results highlight the importance
of symmetry breaking effects in stabilizing electronic states in TBG and open
new avenues for engineering quantum phases in moir\'e systems.

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The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
32
The categories of this paper are: atom-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: chem-ph
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The categories of this paper are: q-alg
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The categories of this paper are: cmp-lg
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The categories of this paper are: nucl-th
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The categories of this paper are: q-fin
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The categories of this paper are: quant-ph
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The categories of this paper are: math-ph
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-ex
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The categories of this paper are: econ
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The categories of this paper are: patt-sol
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The categories of this paper are: eess