Nonequilibrium magnetic properties of oxygenrich LaMnO 3.21 nanoparticles have been investigated by comprehensive magnetic measurements. The composition falls in the metamagnetic canted spin region of the magnetic phase diagram. However, the zerofield cooling memory effect and frequencydependent AC susceptibility reveal a reentrant glassy state at low temperature. In contrast to the superspin glass or cluster glass that reenter from the hightemperature ferromagnetic state in previous studies, analyses based on the power law and Vogel-Fulcher law indicate strongly a conventional spin glass nature. As the magnetic field increases, an anomalous enhancement of the irreversible temperature is observed, suggesting a fieldinduced nonequilibrium magnetic state. These results can be understood by considering the interaction between the antiferromagnetic clusters and the metamagnetic cantedspin matrix inside the nanoparticles.

The structure and magnetic properties are studied in co-doped Cs 2−x K x CuBr 4−x Cl x and pressurized Cs 2 CuBr 4 samples. No structural phase transition is found with doping concentration x 0.1 and pre-compression pressure up to 4.5 GPa. The maximum susceptibility temperature T max of the zero-field-cooling (ZFC) susceptibility curves decreases slightly with increasing doping concentration and pre-compression pressure, indicating only small changes in the exchange coupling constants. However, an unusual enhancement of the magnetic moment deduced from the ZFC susceptibility is observed in both series samples. A maximum increase of 40% is obtained in Cs 1.9 K 0.1 CuBr 3.9 Cl 0.1 sample. The magnetic moment increases almost linearly with decreasing Δ, i.e., defined as the wavenumber difference between the short-and long-bond stretching modes of the CuBr 4 2− tetrahedra in the Raman spectra. The effect is likely due to the recovery of the Cu-3d orbital magnetic moments by strain-induced suppression of Jahn-Teller distortion in CuBr 4 2− tetrahedra.

High-pressure Raman spectra of frustrated antiferromagnet CS2CUCl4 is investigated in a diamond anvil cell. Four characteristic modes of CS2CUCl4 are observed at ambient conditions. As the pressure increases, the sample undergoes a structure phase transition at 5 GPa. After decompressing, the low-pressure Raman spectra are recovered, which indicates a reversible phase transition. We discussed the results in terms of the change of structure with pressure.