Effects of pressure on the magnetic-structural and Griffiths-like transitions in Dy5Si3Ge

Abstract

Magnetization studies have been performed on a polycrystalline sample of Dy 5 Si 3 Ge as a function of an applied magnetic field (up to 50 kOe) and hydrostatic pressure (up to 10 kbar) in the 5-300 K temperature range. The anomalous behavior of the magnetic susceptibility indicates that a Griffiths-like phase exists at low magnetic fields and pressures up to 10 kbar. We present evidence that the high-temperature second-order ferromagnetic transition can be coupled with the low-temperature first-order crystallographic transformation into a single first-order magnetic-crystallographic transformation using a magnetic field and hydrostatic pressure as tuning parameters. The effect of pressure on the Griffiths-like phase is reported and analyzed in the framework of the complex competition between the interslab and intraslab magnetic interactions.

Pressure dependence of the Griffiths-like phase in 5:4 intermetallics

“…We can compare our results with those reported on the GP in Dy 5 Si 3 Ge [17] In all the studied cases, the pressure-induced increase of the T G is lower than that of the corresponding long-range order transition T C,N . The obtained rate values dT G /dP suggest a dependence on the nature of the long-range order (FM or AFM) transition: whereas a moderate pressure-induced increase of the T G is observed when T C , T N are second order (e.g., Gd 5 Ge 4 , Dy 5 Si 3 Ge), a much stronger effect is found when dealing with a first order nature of the transition at T C (e.g., Tb 4.925 La 0.075 Si 2 Ge 2 ).…”

“…To address this, we have performed a complete study of the magnetic properties by measuring low-field dc magnetization as a function of temperature and hydrostatic pressure. We compare our results with those obtained in Dy 5 Si 3 Ge in a previous work [17], as a representative 5:4 compound of M-Griffiths with a second order M-PM → M-AFM transition. These three 5:4 compounds were chosen because they cover the main types of long-range magnetic and structural transitions observed in this family of compounds.…”

“…To date, hydrostatic pressure effects on the true long-range ordered state and first-order structural transitions have been reported. However, less research has been devoted to the effects of pressure on the short-range ordered state (GP) [17].…”

Microstructure study of the rare-earth intermetallic compounds R5(SixGe1-x)4 and R5(SixGe1-x)3

“…[55]. The results of high applied hydrostatic pressure experiments performed on polycrystalline [56] and monocrystalline Er 5 Si 4 [57] showed an extraordinary sensitivity of Er 5 Si 4 to pressure. The crystal structure transition (O(I)→M) temperature T t decreases rapidly at an exceptionally high rate of dT t /dP = -30K/kbar when pressure increases.…”

“…This strong pressure dependence may be due to the absence of a magnetic ordering anomaly in the vicinity of the structural transition. The magnetization isotherms of single crystal Er 5 Si 4 indicate that the easy magnetization direction is along the b-axis [57].The magnetic and crystallographic P-T phase diagram of Er 5 Si 4 is shown in Figure 6 [56].…”