Magneto-optical conductivity and circular dichroism in d-wave altermagnets

Altermagnetism is a magnetic phase characterized by spin-split band structures without spin-orbit coupling (SOC) and rotation symmetry-compensated net magnetization. Here, the authors uncover the magneto-optical properties of a $d$-wave altermagnet. They demonstrate that the spin-polarized bands manifest in the anisotropic spin-resolved optical conductivity, enabling circular dichroism. In the absence (presence) of SOC, only intraband (both intraband and interband) transitions occur which satisfy the selection rule ∆n=\ifmmode\pm\else\textpm\fi{}1 (∆n=\ifmmode\pm\else\textpm\fi{}1,\ifmmode\pm\else\textpm\fi{}3). This research provides valuable insights into the unique optical properties of altermagnetic materials.