Series of bulk magnetic-phase transitions in NaxCoO2: A μSR study

Abstract Using muon spin rotation, well-defined bulk ∼ 100 % magnetic phases in Na x CoO 2 are revealed. A novel magnetic phase is detected for x = 0.85 with the highest transition temperature ever observed for x ⩾ 0.75 . This stresses the diversity of x ⩾ 0.75 magnetic phases and the link between magnetic and structural degrees of freedom. For x = 1.0 , no magnetism is detected as expected for the low spin state of Co 3 + . For the charge-ordered x = 0.50 compound, a cascade of transitions is observed below 85 K.