Observing strong optical nonreciprocity from magnetically doped Dirac semimetals

Many contemporary photonic and optoelectronic technologies rely on strong electromagnetic nonreciprocity at infrared frequencies. However, achieving a strong nonreciprocal effect in the infrared remains extremely challenging due to the lack of materials with inherently large nonreciprocal optical responses. Magnetic Weyl semimetals offer a promising solution, but the choice of materials has thus far been limited. Here, we present a different approach of accessing strong nonreciprocity by doping the Dirac semimetal Cadmium Arsenide (Cd3As2) with a magnetic dopant, Manganese (Mn). We attribute the strong optical nonreciprocity to the collective magnetic ordering of the Mn dopant that creates magnetic Weyl cones by lifting the degeneracy of Dirac cones via time-reversal symmetry breaking. The enabled nonreciprocity exhibits strong tunability through doping concentration and external magnetic fields, providing a new material platform and design rational for accessing strong electromagnetic nonreciprocity. Nonreciprocity is a key feature of numerous photonic and optoelectronic technologies, yet there is a critical lack of materials exhibiting intrinsic optical non-reciprocity. Here, Nabavi and coauthors present a material design approach to overcome this, doping the Dirac semimetal, Cadmium Arsenide, with Manganese, generating magnetic Weyl cones and resulting strong non-reciprocity.