Bulk band structure of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>Ru</mml:mi> <mml:msub> <mml:mi mathvariant="normal">O</mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:math> measured with soft x-ray angle-resolved photoemission spectroscopy
Zihan Lin, Dong Chen, Wenlong Lu, Xin Liang, Shiyu Feng, Kohei Yamagami, Jacek Osiecki, Mats Leandersson, T. Balasubramanian, Junwei Liu, Claudia Felser, Junzhang Ma
Abstract
Altermagnetism exhibits unique physical properties such as spin-momentum locking, anomalous Hall effect, nontrivial topological phase, and giant magnetoresistance. Among all the predicted candidates, several room-temperature altermagnets are suggested to host significant potential applications. <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mrow> <a:mi>Ru</a:mi> <a:msub> <a:mi mathvariant="normal">O</a:mi> <a:mn>2</a:mn> </a:msub> </a:mrow> </a:math> has been proposed as the most promising candidate. However, recently, there is intense debate about whether <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"> <c:mrow> <c:mi>Ru</c:mi> <c:msub> <c:mi mathvariant="normal">O</c:mi> <c:mn>2</c:mn> </c:msub> </c:mrow> </c:math> exhibits magnetic order or not. Experiments by several different technologies claim the collinear magnetic order and spin-splitting-induced effects. However, very recent muon spin resonance (μSR) results reveal no magnetic order in <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"> <e:mrow> <e:mi>Ru</e:mi> <e:msub> <e:mi mathvariant="normal">O</e:mi> <e:mn>2</e:mn> </e:msub> </e:mrow> </e:math> , which indicates that the time-reversal symmetry is not broken. Direct observation of the high-resolution bulk band structure is absent to date but essential to investigate the electronic structure of <g:math xmlns:g="http://www.w3.org/1998/Math/MathML"> <g:mrow> <g:mi>Ru</g:mi> <g:msub> <g:mi mathvariant="normal">O</g:mi> <g:mn>2</g:mn> </g:msub> </g:mrow> </g:math> . In this study, utilizing soft x-ray angle-resolved photoemission spectroscopy, we report systematic direct experimental observation of bulk band structure of <i:math xmlns:i="http://www.w3.org/1998/Math/MathML"> <i:mrow> <i:mi>Ru</i:mi> <i:msub> <i:mi mathvariant="normal">O</i:mi> <i:mn>2</i:mn> </i:msub> </i:mrow> </i:math> .