Spin-triplet superconductivity in K<sub>2</sub>Cr<sub>3</sub>As<sub>3</sub>.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 34936458.
- Also identified by DOI 10.1126/sciadv.abl4432 and PMC identifier 8694604.
- Licence recorded as CC BY-NC.
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Abstract
A spin-triplet superconductor can harbor Majorana bound states that can be used in topological quantum computing. Recently, K<sub>2</sub>Cr<sub>3</sub>As<sub>3</sub> and its variants with critical temperature <i>T</i><sub>c</sub> as high as 8 kelvin have emerged as a new class of superconductors with ferromagnetic spin fluctuations. Here, we report a discovery in K<sub>2</sub>Cr<sub>3</sub>As<sub>3</sub> single crystal that the spin susceptibility measured by <sup>75</sup>As Knight shift below <i>T</i><sub>c</sub> is unchanged with the magnetic field <i>H</i><sub>0</sub> applied in the <i>ab</i> plane but vanishes toward zero temperature when <i>H</i><sub>0</sub> is along the <i>c</i> axis, which unambiguously establishes this compound as a spin-triplet superconductor described by a vector order parameter <math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mover accent="true"><mi>d</mi><mo stretchy="true">→</mo></mover></mrow></semantics></math> parallel to the <i>c</i> axis. Combining with point nodal gap, we show that K<sub>2</sub>Cr<sub>3</sub>As<sub>3</sub> is a new platform for the study of topological superconductivity and its possible technical application.