Large Nernst effect in Te-based van der Waals materials

Layered van der Waals tellurides reveal topologically nontrivial properties that give rise to unconventional magneto-transport phenomena. Additionally, their semimetallic character with high mobility makes them promising candidates for large magneto-thermoelectric effects. Remarkable studies on the very large and unconventional Nernst effect in <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msub><a:mi>WTe</a:mi><a:mn>2</a:mn></a:msub></a:math> have been reported, raising questions about whether this property is shared across the entire family of van der Waals tellurides. In this study, systematic measurements of the Nernst effect in telluride van der Waals Weyl semimetals are presented. Large linear Nernst coefficients in <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:msub><b:mi>WTe</b:mi><b:mn>2</b:mn></b:msub></b:math> and <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:msub><c:mi>MoTe</c:mi><c:mn>2</c:mn></c:msub></c:math> are identified, and moderate Nernst coefficients with nonlinear behavior in magnetic fields are observed in <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"><d:mrow><d:msub><d:mi mathvariant="normal">W</d:mi><d:mrow><d:mn>0.65</d:mn></d:mrow></d:msub><d:msub><d:mi>Mo</d:mi><d:mrow><d:mn>0.35</d:mn></d:mrow></d:msub><d:msub><d:mi>Te</d:mi><d:mn>2</d:mn></d:msub></d:mrow><d:mo>,</d:mo><d:mo> </d:mo><d:msub><d:mi>TaIrTe</d:mi><d:mn>4</d:mn></d:msub></d:math>, and <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"><f:msub><f:mi>TaRhTe</f:mi><f:mn>4</f:mn></f:msub></f:math>. Within this sample set, a correlation between the dominant linear-in-magnetic-field component of the Nernst coefficient and mobility is established, aligning with the established Nernst scaling framework, although with a different scaling factor compared with existing literature. This enhancement might be caused by the shared favorable electronic band structure of this family of materials. Conversely, the nonlinear component of the Nernst effect in a magnetic field could not be correlated with mobility. This nonlinear term is almost absent in the binary compounds, suggesting a multiband origin and strong compensation between electron-like and hole-like carriers. This comprehensive study highlights the potential of van der Waals tellurides for thermoelectric conversion.