Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Prague, Czech Republic
Bernd Büchner
Leibniz Institute for Solid State and Materials Research, IFW Dresden, Helmholtzstr. 20, 01069 Dresden, Germany
Joseph Dufouleur
Leibniz Institute for Solid State and Materials Research, IFW Dresden, Helmholtzstr. 20, 01069 Dresden, Germany
Martin Kamp
Physikalisches Institut, Universität Würzburg, D-97074 Würzburg, Germany and Röntgen Center for Complex Material Systems, Universität Würzburg, D-97074 Würzburg, Germany
Vedran Jovic
Earth Resources and Materials, Institute of Geological and Nuclear Science, Lower Hutt 5010, New Zealand and MacDiarmid Institute for Advanced Materials and Nanotechnology, Wellington 6012, New Zealand
Libor Smejkal
Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Prague, Czech Republic
Jairo Sinova
Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Prague, Czech Republic
Ralph Claessen
Würzburg-Dresden Cluster of Excellence ct.qmat, Dresden, Germany
Tomas Jungwirth
Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Prague, Czech Republic
Simon Moser
Würzburg-Dresden Cluster of Excellence ct.qmat, Dresden, Germany
Helena Reichlova
Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Prague, Czech Republic
Louis Veyrat
Leibniz Institute for Solid State and Materials Research, IFW Dresden, Helmholtzstr. 20, 01069 Dresden, Germany
Observations of the anomalous Hall effect in RuO2 and MnTe have demonstrated unconventional time-reversal symmetry breaking in the electronic structure of a recently identified new class of compensated collinear magnets, dubbed altermagnets. While in MnTe, the unconventional anomalous Hall signal accompanied by a vanishing magnetization is observable at remanence, the anomalous Hall effect in RuO2 is excluded by symmetry for the Néel vector pointing along the zero-field [001] easy-axis. Guided by a symmetry analysis and ab initio calculations, a field-induced reorientation of the Néel vector from the easy-axis toward the [110] hard-axis was used to demonstrate the anomalous Hall signal in this altermagnet. We confirm the existence of an anomalous Hall effect in our RuO2 thin-film samples, whose set of magnetic and magneto-transport characteristics is consistent with the earlier report. By performing our measurements at extreme magnetic fields up to 68 T, we reach saturation of the anomalous Hall signal at a field Hc ≃ 55 T that was inaccessible in earlier studies but is consistent with the expected Néel-vector reorientation field.
