While moiré phenomena have been extensively studied in low-carrier-density systems such as semiconductors, their implications for metallic systems with large Fermi surfaces remain largely unexplored. Using GPU-accelerated large-scale ab-initio quantum transport simulations, we investigate spin transport in two distinct platforms: twisted bilayer MoTe2 (semiconductor) and NbX2 (X = S, Se; metals). In twisted MoTe2, the spin Hall conductivity (SHC) evolves from <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$4\frac{e}{4\pi }$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>4</mn> <mfrac> <mrow> <mi>e</mi> </mrow> <mrow> <mn>4</mn> <mi>π</mi> </mrow> </mfrac> </mrow> </math></EquationSource> </InlineEquation> at 5.09° to <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$10\frac{e}{4\pi }$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>10</mn> <mfrac> <mrow> <mi>e</mi> </mrow> <mrow> <mn>4</mn> <mi>π</mi> </mrow> </mfrac> </mrow> </math></EquationSource> </InlineEquation> at 1.89°. Remarkably, in heavily doped metallic regimes where isolated Chern bands are absent, we observe a universal amplification of the SHC arising from Fermi surface reconstruction under a long-wavelength potential, with the peak SHC tripling from <InlineEquation ID="IEq3"> <EquationSource Format="TEX">$6\frac{e}{4\pi }$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>6</mn> <mfrac> <mrow> <mi>e</mi> </mrow> <mrow> <mn>4</mn> <mi>π</mi> </mrow> </mfrac> </mrow> </math></EquationSource> </InlineEquation> at 5.09° to <InlineEquation ID="IEq4"> <EquationSource Format="TEX">$17\frac{e}{4\pi }$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>17</mn> <mfrac> <mrow> <mi>e</mi> </mrow> <mrow> <mn>4</mn> <mi>π</mi> </mrow> </mfrac> </mrow> </math></EquationSource> </InlineEquation> at 3.89°. For moiré metals like twisted NbX2, we identify a record SHC of −5200 (ℏ/e)S/cm, surpassing all known bulk materials.

Universal giant spin Hall effect in moiré metal

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2026年2月26日

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Ning Mao,
Cheng Xu,
Ting Bao,
Nikolai Peshcherenko,
Claudia Felser,
Yang Zhang

摘要

While moiré phenomena have been extensively studied in low-carrier-density systems such as semiconductors, their implications for metallic systems with large Fermi surfaces remain largely unexplored. Using GPU-accelerated large-scale ab-initio quantum transport simulations, we investigate spin transport in two distinct platforms: twisted bilayer MoTe₂ (semiconductor) and NbX₂ (X = S, Se; metals). In twisted MoTe₂, the spin Hall conductivity (SHC) evolves from $4\frac{e}{4\pi }$ $4 \frac{e}{4 π}$ at 5.09° to $10\frac{e}{4\pi }$ $10 \frac{e}{4 π}$ at 1.89°. Remarkably, in heavily doped metallic regimes where isolated Chern bands are absent, we observe a universal amplification of the SHC arising from Fermi surface reconstruction under a long-wavelength potential, with the peak SHC tripling from $6\frac{e}{4\pi }$ $6 \frac{e}{4 π}$ at 5.09° to $17\frac{e}{4\pi }$ $17 \frac{e}{4 π}$ at 3.89°. For moiré metals like twisted NbX₂, we identify a record SHC of −5200 (ℏ/e)S/cm, surpassing all known bulk materials.