Role of atomic site for the phase transition in kagome lattice compounds: A case study of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mi>Sc</mml:mi><mml:msub><mml:mi mathvariant="normal">V</mml:mi><mml:mn>6</mml:mn></mml:m

Vanadium-based kagome metal of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:mi>Sc</a:mi><a:msub><a:mi mathvariant="normal">V</a:mi><a:mn>6</a:mn></a:msub><a:mi mathvariant="normal">S</a:mi><a:msub><a:mi mathvariant="normal">n</a:mi><a:mn>6</a:mn></a:msub></a:mrow></a:math> has been of current interest as it features unique charge density wave (CDW) ordering accompanied by a structural phase transition, indicating the importance of lattice distortion for the onset of CDW order. To unveil the role of each individual atomic site for the phase transition, we employed a local probe through the nuclear magnetic resonance (NMR) measurements in which the NMR signals from <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"><e:mrow><e:mmultiscripts><e:mi>Sc</e:mi><e:mprescripts/><e:none/><e:mn>45</e:mn></e:mmultiscripts></e:mrow><e:mo>,</e:mo><e:mo> </e:mo><e:mrow><e:mmultiscripts><e:mi mathvariant="normal">V</e:mi><e:mprescripts/><e:none/><e:mn>51</e:mn></e:mmultiscripts></e:mrow></e:math>, and <g:math xmlns:g="http://www.w3.org/1998/Math/MathML"><g:mrow><g:mmultiscripts><g:mi>Sn</g:mi><g:mprescripts/><g:none/><g:mn>119</g:mn></g:mmultiscripts></g:mrow></g:math> nuclei in both normal and CDW states were observed. From the comparison between the quadrupole splitting of <h:math xmlns:h="http://www.w3.org/1998/Math/MathML"><h:mrow><h:mmultiscripts><h:mi>Sc</h:mi><h:mprescripts/><h:none/><h:mn>45</h:mn></h:mmultiscripts></h:mrow></h:math> and <i:math xmlns:i="http://www.w3.org/1998/Math/MathML"><i:mrow><i:mmultiscripts><i:mi mathvariant="normal">V</i:mi><i:mprescripts/><i:none/><i:mn>51</i:mn></i:mmultiscripts></i:mrow></i:math> NMR satellite lines, a noticeable increase in the <k:math xmlns:k="http://www.w3.org/1998/Math/MathML"><k:mrow><k:mmultiscripts><k:mi>Sc</k:mi><k:mprescripts/><k:none/><k:mn>45</k:mn></k:mmultiscripts></k:mrow></k:math> quadrupole frequency below the transition temperature was identified. The finding can be accounted for by the structural distortion mainly involving the displacement of Sc and Sn atoms along the crystal <l:math xmlns:l="http://www.w3.org/1998/Math/MathML"><l:mi>c</l:mi></l:math> axis. From the analysis of the temperature dependences of the NMR shift, we quantitatively obtained the change in the electronic states for each atom associated with the phase transition. In particular, we demonstrated a marked reduction in the V <m:math xmlns:m="http://www.w3.org/1998/Math/MathML"><m:mrow><m:mn>3</m:mn><m:mi>d</m:mi></m:mrow></m:math> density of states at the Femi level, which can be rationalized as a manifestation of the structural transition. Remarkably, we resolved three <n:math xmlns:n="http://www.w3.org/1998/Math/MathML"><n:mrow><n:mmultiscripts><n:mi>Sn</n:mi><n:mprescripts/><n:none/><n:mn>119</n:mn></n:mmultiscripts></n:mrow></n:math> NMR resonance lines corresponding to three nonequivalent crystallographic Sn sites and therefore estimated the variation in the <o:math xmlns:o="http://www.w3.org/1998/Math/MathML"><o:mrow><o:mn>5</o:mn><o:mi>s</o:mi></o:mrow></o:math> electronic states of each Sn atom in <p:math xmlns:p="http://www.w3.org/1998/Math/MathML"><p:mrow><p:mi>Sc</p:mi><p:msub><p:mi mathvariant="normal">V</p:mi><p:mn>6</p:mn></p:msub><p:mi mathvariant="normal">S</p:mi><p:msub><p:mi mathvariant="normal">n</p:mi><p:mn>6</p:mn></p:msub></p:mrow></p:math>.