Nonvolatile anomalous Nernst effect in Mn 5 Si 3 with a collinear Néel vector

For magnetic-resistant and ultrafast transverse thermoelectric converters, antiferromagnets with a collinear N\'eel vector have unique advantages but their anomalous Nernst effect (ANE), as the fundamental requirement, remains unachieved due to the spin-degenerated bands. Here, we realize the nonvolatile ANE in an altermagnet from ${\mathrm{Mn}}_{5}{\mathrm{Si}}_{3}$ thin films with a collinear N\'eel vector under strain, where the Berry curvature from the intersections of spin-splitting bands (instead of a tiny net moment) determines the anomalous Nernst conductivity. The ANE undergoes a sixfold enhancement via doping, most likely due to the raised Fermi level. Order parameter fluctuations induce unique temperature dependence, which also applies to other suitable altermagnets. Our work not only fills a longstanding gap by observing the nonvolatile ANE in material with a collinear N\'eel vector but also enlightens thermoelectric physics related to spin-splitting bands.