Na-vacancies-induced magnetism in NaxMnO2

The magnetism of layered NaxMnO2 with space group P63/mmc is investigated by first-principles calculation and magnetic measurement. Results indicate that NaMnO2 without any Na-vacancies posses the anti-ferromagnetic metal state. And along with Na-vacancies formed, the magnetism and electronic properties of NaxMnO2 show rich change, which undergo the change of AFM -> FM -> AFM and metal -> semiconductor, respectively. Magnetic measurement of Na0.806MnO2-delta with space group P63/mmc also shows that have thin hysteresis and remanent under 5 K. Hence, Na0.806MnO2-delta presents the ferromagnetic metal state under low temperature roofing in the Mn3--O2--Mn4+ double exchange, which is agreement with theoretical results.