Observation of a spontaneous anomalous Hall response in the Mn5Si3 d-wave altermagnet candidate
Helena Reichlová, Rafael Lopes Seeger, Rafael González‐Hernández, Ismaïla Kounta, Richard Schlitz, Dominik Kriegner, Philipp Ritzinger, Michaela Lammel, Miina Leiviskä, Anna Birk Hellenes, K. Olejník, V. Petřı́ček, Petr Doležal, Lukáš Horák, Eva Schmoranzerová, Antonín Baďura, Sylvain Bertaina, Andy Thomas, V. Baltz, Lisa Michez, Jairo Sinova, Sebastian T. B. Goennenwein, T. Jungwirth, Libor Šmejkal
Abstract
Abstract Phases with spontaneous time-reversal ( $${{{{{{{\mathcal{T}}}}}}}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>T</mml:mi> </mml:math> ) symmetry breaking are sought after for their anomalous physical properties, low-dissipation electronic and spin responses, and information-technology applications. Recently predicted altermagnetic phase features an unconventional and attractive combination of a strong $${{{{{{{\mathcal{T}}}}}}}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>T</mml:mi> </mml:math> -symmetry breaking in the electronic structure and a zero or only weak-relativistic magnetization. In this work, we experimentally observe the anomalous Hall effect, a prominent representative of the $${{{{{{{\mathcal{T}}}}}}}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>T</mml:mi> </mml:math> -symmetry breaking responses, in the absence of an external magnetic field in epitaxial thin-film Mn 5 Si 3 with a vanishingly small net magnetic moment. By symmetry analysis and first-principles calculations we demonstrate that the unconventional d-wave altermagnetic phase is consistent with the experimental structural and magnetic characterization of the Mn 5 Si 3 epilayers, and that the theoretical anomalous Hall conductivity generated by the phase is sizable, in agreement with experiment. An analogy with unconventional d-wave superconductivity suggests that our identification of a candidate of unconventional d-wave altermagnetism points towards a new chapter of research and applications of magnetic phases.