<p>The recent discovery of high-transition temperature (<i>T</i><sub>c</sub>) superconductivity in pressurized La<sub>3</sub>Ni<sub>2</sub>O<sub>7</sub> bulk crystals has attracted keen attention for its characteristic energy diagram of <i>e</i><sub>g</sub> orbitals containing nearly half-filled&#xa0;<InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="42005_2025_2154_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="48" /> </InlineMediaObject> <EquationSource Format="TEX">\({d}_{{3}{z}^{2}-{r}^{2}}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mrow> <mi>d</mi> </mrow> <mrow> <mn>3</mn> <msup> <mrow> <mi>z</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msup> <mo>−</mo> <msup> <mrow> <mi>r</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msup> </mrow> </msub> </math></EquationSource> </InlineEquation> and quarter-filled <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="42005_2025_2154_Article_IEq2.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="43" /> </InlineMediaObject> <EquationSource Format="TEX">\({d}_{{x}^{2}-{y}^{2}}\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mrow> <mi>d</mi> </mrow> <mrow> <msup> <mrow> <mi>x</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msup> <mo>−</mo> <msup> <mrow> <mi>y</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msup> </mrow> </msub> </math></EquationSource> </InlineEquation> orbitals. This finding provides valuable insights into the orbital contributions and interlayer interactions in double NiO<sub>6</sub> octahedrons that further provides a chance to control the electronic structure via varying ligand field. Here, we demonstrate that strain-tuning of the <i>T</i><sub>c</sub> over a range of 50 K with La<sub>3</sub>Ni<sub>2</sub>O<sub>7</sub> films on different oxide substrates under 20 GPa. As the <i>c</i>/<i>a</i> ratio increases, the onset <i>T</i><sub>c</sub> systematically increases from 10 K in the tensile-strained film on SrTiO<sub>3</sub> to the highest value about 60 K in the compressively strained film on LaAlO<sub>3</sub>. These systematic variations suggest that strain-engineering is a promising approach for expanding the superconductivity in bilayer nickelates with tuning the energy diagram for achieving high-<i>T</i><sub>c</sub> superconductivity.</p>

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Strain-tuning for superconductivity in La3Ni2O7 thin films

  • Motoki Osada,
  • Chieko Terakura,
  • Akiko Kikkawa,
  • Masamichi Nakajima,
  • Hsiao-Yi Chen,
  • Yusuke Nomura,
  • Yoshinori Tokura,
  • Atsushi Tsukazaki

摘要

The recent discovery of high-transition temperature (Tc) superconductivity in pressurized La3Ni2O7 bulk crystals has attracted keen attention for its characteristic energy diagram of eg orbitals containing nearly half-filled  \({d}_{{3}{z}^{2}-{r}^{2}}\) d 3 z 2 r 2 and quarter-filled \({d}_{{x}^{2}-{y}^{2}}\) d x 2 y 2 orbitals. This finding provides valuable insights into the orbital contributions and interlayer interactions in double NiO6 octahedrons that further provides a chance to control the electronic structure via varying ligand field. Here, we demonstrate that strain-tuning of the Tc over a range of 50 K with La3Ni2O7 films on different oxide substrates under 20 GPa. As the c/a ratio increases, the onset Tc systematically increases from 10 K in the tensile-strained film on SrTiO3 to the highest value about 60 K in the compressively strained film on LaAlO3. These systematic variations suggest that strain-engineering is a promising approach for expanding the superconductivity in bilayer nickelates with tuning the energy diagram for achieving high-Tc superconductivity.