Microscopic magnetic and structural nature of spinel Li [Lix Mn2-x] O4

The magnetic nature of the spinel antiferromagnet Li [Lix Mn2-x] O4 with x=0-0.15 has been studied with muon-spin rotation and relaxation (μ+ SR) spectroscopy. Both weak-transverse-field and zero-field μ+ SR measurements indicate that the whole sample enters into a static disordered magnetic phase below TN for all the samples measured; TN =61 K for LiMn2 O4, but 27-23 K for the x=0.05-0.15 samples. It was also clarified that both the field distribution width and the field fluctuation rate show a clear change at the Jahn-Teller (JT) transition temperature (TJT =280 K) for LiMn2 O4, and a short-range cooperative JT distortion appears below 280 K even for Li [Li0.15 Mn1.85] O4.