Fermi Surface of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>RuO</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:mrow> </mml:math> Measured by Quantum Oscillations
Z. Wu, Mengmeng Long, Han‐Yi Chen, Shubhankar Paul, Hisakazu Matsuki, Oleksandr Zheliuk, U. Zeitler, Gang Li, Rui Zhou, Zengwei Zhu, David Graf, Theodore I. Weinberger, F. M. Grosche, Y. Maeno, Alexander G. Eaton
Abstract
The metallic oxide <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mrow> <a:msub> <a:mrow> <a:mi>RuO</a:mi> </a:mrow> <a:mrow> <a:mn>2</a:mn> </a:mrow> </a:msub> </a:mrow> </a:math> has emerged as a promising altermagnet candidate, owing to reports of this material hosting antiferromagnetic ordering accompanied by a spin-split electronic band structure characteristic of time-reversal symmetry breaking. However, recent studies have robustly questioned this scenario. Here we map the Fermi surface of pristine single-crystalline <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mrow> <c:msub> <c:mrow> <c:mi>RuO</c:mi> </c:mrow> <c:mrow> <c:mn>2</c:mn> </c:mrow> </c:msub> </c:mrow> </c:math> . By measuring magnetic quantum oscillations of a bulk thermodynamic property, our study resolves the electronic structure present in the bulk of <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mrow> <e:msub> <e:mrow> <e:mi>RuO</e:mi> </e:mrow> <e:mrow> <e:mn>2</e:mn> </e:mrow> </e:msub> </e:mrow> </e:math> . Several Fermi sheets are discerned, with a range of effective quasiparticle masses up to 5 times that of the bare electron mass. We compare our measurements with the predictions for altermagnetic and nonmagnetic Fermi surfaces deduced from density functional theory calculations. The quantum oscillatory frequency spectra correspond very poorly to the profile expected for the case of altermagnetism; by contrast, they correspond well to the nonmagnetic scenario. Our findings place significant constraints on the bulk magnetic properties of <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:mrow> <g:msub> <g:mrow> <g:mi>RuO</g:mi> </g:mrow> <g:mrow> <g:mn>2</g:mn> </g:mrow> </g:msub> </g:mrow> </g:math> and strongly suggest that this material is an itinerant electron paramagnet.