Magnetic properties and specific heat of new spin glass Mn0.5Fe0.5PS3

Abstract

We have found spin glass phenomena in a layered Mn0.5Fe0.5PS3 compound and investigated its magnetic properties and specific heat. The temperature dependence of the zero field cooled (ZFC) magnetization along the easy axis, M∥ under dc applied field Ha below 1 kOe shows a cusp at Tg=32.6 K. The FC and ZFC curves measured at Ha below 1 kOe separate at almost the same temperature as Tg. For Ha larger than 1 kOe, the temperature at which FC and ZFC curves separate deviates from Tg and shifts toward lower temperature and the peak becomes broader. Magnetic hysteresis is still observed above 70 kOe at 2 K. The remarkable feature of this spin glass phase is that the spin freezing is not suppressed up to a rather high magnetic field compared with similar spin glass (Mn,Fe)TiO3. The cusp temperature of χ′(ω) does not show magnetic field amplitude dependence from 1 to 10 Oe and increases with an increase in frequency, obeying the Vogel–Fulcher rule. The temperature dependence of χ″(ω) shows two extra peaks at Tm1 and Tm2 below Tg. The time dependence of thermoremanent magnetization MTRM below Tg shows power law dependence. The value of the molar specific heat is about an order of magnitude larger than that of MnPS3 and FePS3 at 2 K. The T-linear term characteristic of spin glass is observed below about 10 K. The temperature dependence of the magnetic specific heat shows no anomaly at Tg, Tm1=9 and Tm2=16 K, and shows two peaks at Tc1=13 and Tc2=67 K.