High‐Performance Mid‐Wave Infrared Photothermoelectric Response in Magnetic Semiconductors MnTe and MnTe ₂ Crystals

Abstract Photothermoelectric (PTE) detectors are considered a promising alternative to infrared photon detectors due to their broadband response, room‐temperature operation, and self‐powered. Theoretically, altermagnetic/noncoplanar‐antiferromagnetic materials MnTe/MnTe ₂ can generate significant PTE effect in the infrared band because of their pronounced thermoelectric properties, and rich optical absorptions coming from the complex electronic structure due to spin‐orbit‐coupling and Zeeman effect. Here, the PTE effect of MnTe and MnTe ₂ crystals are experimentally explored for the first time. Both MnTe and MnTe ₂ PTE photodetectors, without any artificial micro‐/nano‐structure, demonstrate excellent performance in the broadband of electromagnetic waves ranging from 444 to 3800 nm. For example, MnTe remarkably exhibits a peak responsivity of 60 mV W ⁻¹ (1.6 mA W ⁻¹ ) and detectivity of 8.3 × 10 ⁶ Jones at 3600 nm, superior to most PTE detectors made by bulk thermoelectric and topological‐semimetal materials. The experimental photoresponses are quite close to theoretical simulations. Beneficial to excellent PTE performance of MnTe, as device demonstrations, high‐precision imaging and pronounced human radiation detection can be achieved by a prototype MnTe photodetector. This work demonstrates the promising potential of MnTe and MnTe ₂ crystals for low‐power mid‐infrared photodetection at room temperature, as well as the multifunctionalities of altermagnetic and noncoplanar‐antiferromagnetic materials.