Uniaxial Stress Enhanced Anisotropic Magnetoresistance and Superconductivity in the Kagome Superconductor LaRu₃Si₂.

Abstract

To elucidate how kagome electronic structure governs quantum ground states, we introduce a unique approach combining in-plane uniaxial stress tuning, magnetotransport, and first-principles calculations to uncover its impact on superconducting and normal-state properties in <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics> <mrow><msub><mi>LaRu</mi> <mn>3</mn></msub> <msub><mi>Si</mi> <mn>2</mn></msub> </mrow> <annotation>${\rm LaRu}_{3}{\rm Si}_{2}$</annotation></semantics> </math> . We identify a pronounced anisotropy in both the upper critical field and the normal-state magnetoresistance, indicating strong electronic anisotropy despite the three-dimensional crystal structure. Furthermore, we find that the superconducting transition temperature <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics><msub><mi>T</mi> <mi>c</mi></msub> <annotation>$T_{\rm c}$</annotation></semantics> </math> increases under in-plane stress applied within the kagome plane, although the enhancement is modest, reaching approximately 0.3 K at 0.6 GPa. Furthermore, the absolute magnetoresistance exhibits a pronounced increase from about 22 <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mo>%</mo> <annotation>${\%}$</annotation></semantics> </math> at zero stress to 35 <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mo>%</mo> <annotation>${\%}$</annotation></semantics> </math> at 0.6 GPa, indicating a substantial modification of the normal state above <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics><msub><mi>T</mi> <mi>c</mi></msub> <annotation>$T_{\rm c}$</annotation></semantics> </math> . The simultaneous enhancement of both <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics><msub><mi>T</mi> <mi>c</mi></msub> <annotation>$T_{\rm c}$</annotation></semantics> </math> and magnetoresistance under stress suggests a positive correlation between superconductivity and normal-state electronic and magnetic properties in <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics> <mrow><msub><mi>LaRu</mi> <mn>3</mn></msub> <msub><mi>Si</mi> <mn>2</mn></msub> </mrow> <annotation>${\rm LaRu}_{3}{\rm Si}_{2}$</annotation></semantics> </math> . Detailed calculations demonstrate that the stress-induced evolution of superconductivity and magnetotransport arises from the cooperative interplay between modifications of the total density of states, kagome flat-band physics, and anisotropic electronic response. In particular, the pronounced enhancement of magnetoresistance is closely linked to the stress-driven downward shift of the Ru <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics><mrow><mi>d</mi> <msup><mi>z</mi> <mn>2</mn></msup> </mrow> <annotation>$dz^{2}$</annotation></semantics> </math> kagome-derived flat band.