Probing the Meissner Effect in Microscale Two-Dimensional van der Waals Superconductors.

Abstract

(2D) van der Waals (vdW) superconductors provide a platform for investigating unconventional superconductivity, topological states, and low-power quantum devices. However, due to their extremely small volume and weak magnetic signals, their superconductivity has primarily been assessed through zero resistance, while the Meissner effect remains largely unexplored. Here, we demonstrate that dynamic cantilever magnetometry (DCM) can be used to probe the intrinsic Meissner diamagnetism in 2D vdW superconductors. A theoretical model is first established to quantitatively extract magnetization and susceptibility. Building on this, using 2M-WS₂ as a model system, a clear magnetization hysteresis loop characteristic of type-II superconductivity is resolved. Meanwhile, susceptibility is also detected down to a thickness of 5.7 nm, revealing a screening efficiency of about 89.9% at 4.6 mT, indicative of nearly complete diamagnetic screening. We analyze that DCM achieves a magnetization sensitivity of <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics><mrow><mo>∼</mo> <mspace></mspace> <mspace></mspace> <mn>1.1</mn> <mo>×</mo> <msup><mn>10</mn> <mrow><mo>-</mo> <mn>17</mn></mrow> </msup> <mspace></mspace> <mi>A</mi> <mo>·</mo> <msup><mi>m</mi> <mn>2</mn></msup> </mrow> <annotation>$\sim\!\! 1.1 \times {{10}^{ - 17}}\ {\mathrm{A}} \cdot {{{\mathrm{m}}}^2}$</annotation></semantics> </math> and susceptibility sensitivity of <math xmlns="http://www.w3.org/1998/Math/MathML"> <semantics><mrow><mo>∼</mo> <mspace></mspace> <mn>9.4</mn> <mo>×</mo> <msup><mn>10</mn> <mrow><mo>-</mo> <mn>17</mn></mrow> </msup> <mspace></mspace> <mi>A</mi> <mo>·</mo> <msup><mi>m</mi> <mn>2</mn></msup> <mo>/</mo> <mi>T</mi></mrow> <annotation>$\sim\! 9.4 \times {{10}^{ - 17}}\ {\mathrm{A}} \cdot {{{\mathrm{m}}}^2}/{\mathrm{T}}$</annotation></semantics> </math> . Our results provide crucial magnetic signatures of the Meissner effect in 2D vdW superconductors and highlight the capability of DCM for magnetic validation of superconductivity in low-dimensional materials.