Fermi surface and effective masses of IrO2 probed by de Haas-van Alphen quantum oscillations

Iridium-containing conducting materials are widely investigated for their strong spin-orbit coupling and potential topological properties. Recently the commonly used electrode material iridium dioxide was found to host a large spin-Hall conductivity and was shown to support Dirac nodal lines. Here we present quantum-oscillation experiments on high-quality <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:msub><a:mi>IrO</a:mi><a:mn>2</a:mn></a:msub></a:math> single crystals using the de Haas-van Alphen effect measured using torque magnetometry with a piezoresistive microcantilever as well as density functional theory-based band-structure calculations. The angle, temperature, and field dependencies of the oscillations and the calculated band dispersion provide valuable information on the properties of the charge carriers, including the Fermi-surface geometry and electronic correlations. Comparison of experimental results to calculations allows us to assigns the observed de Haas-van Alphen frequencies to the calculated Fermi surface topology. We find that the effective masses of <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:msub><b:mi>IrO</b:mi><b:mn>2</b:mn></b:msub></b:math> are enhanced compared to the rest electron mass <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:msub><c:mi>m</c:mi><c:mi>e</c:mi></c:msub></c:math>, ranging from 1.9 to 3.0 <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"><d:msub><d:mi>m</d:mi><d:mi>e</d:mi></d:msub></d:math>, whereas the scattering times indicate excellent sample quality. We discuss our results in context with recent ARPES and band-structure calculation results that found Dirac nodal lines in <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"><e:msub><e:mi>IrO</e:mi><e:mn>2</e:mn></e:msub></e:math> and compare the effective masses and other electronic properties to those of similar materials like the nodal chain metal <f:math xmlns:f="http://www.w3.org/1998/Math/MathML"><f:msub><f:mi>ReO</f:mi><f:mn>2</f:mn></f:msub></f:math> in which Dirac electrons with very light effective masses have been observed.