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The magnetic properties of the candidate lithium-ion battery cathode materials Li _2 MnSiO _4 have been studied experimentally using static and pulsed high magnetic fields. A field-induced magnetic transition is observed in low temperature region, in which a saturation magnetization is observed above 27 T which confirms that the Mn-ion has a dominant low spin state with a saturated magnetic moment of ∼3.1 μ _B /Mn. With the change of temperature and magnetic field, the Li _2 MnSiO _4 shows a complex magnetic phase transition. Considering to the coupling between spin, charge and orbital, the field-induced magnetic transition may affect the charge-discharge behavior of the cathode material, thus, the study is expected to explore the possibility and stability of the candidate lithium-ion battery cathode materials used in the low temperature and high magnetic field circumstance and its performance degradation.

The magnetic properties and dielectric polarization of CuFe1−xGaxO2 with various nonmagnetic Ga3+ doping levels have been measured in a wide magnetic field region, in which the observed experiment results have been explained by the consequence of the change in exchange interaction, dilution effect, and partial reduction of spin frustration. Compared with pure CuFeO2, doped nonmagnetic Ga3+ ions have an important effect on magnetization and polarization behavior and lead to an enhanced magnetoelectric coupling, especially, an enhanced spontaneous polarization has been observed in the doping amount of 0.02 and 0.05. This magnetoelectric effect appears mainly in the ferroelectric incommensurate magnetic phase region due to the noncollinear magnetic structure with a proper helical order in the CuFeO2. Based on the magnetization and polarization data, a magnetic phase diagram of temperature, magnetic field, and the doping amount are obtained. [ABSTRACT FROM AUTHOR]