Pressure dependent magnetic, AC susceptibility and electrical properties of Nd₇Pd₃

Abstract

The effects of pressure on the magnetization and isothermal entropy change, AC susceptibility, and resistivity for Nd 7 Pd 3 have been studied. Nd 7 Pd 3 shows three magnetic transitions T t (¼15 K), T C (¼34 K), and T N (¼38 K) at a pressure of zero bar. T C and T N are very sensitive to the pressure and rates of change of T C and T N with respect to pressure, i.e., dT C /dp and dT N /dp are À1.906 K kbar À1 and À0.313 K kbar À1 respectively, whereas T t is insensitive to pressure change. It has also been observed that the isothermal entropy change is also sensitive to pressure. Below 15 K, an indication of spin glass nature in the AC susceptibility data is seen. The time dependent magnetization at low temperatures also supports the spin glass nature, but at high temperatures it indicates a complex nature. The electrical resistivity data has been fitted to the relation r ¼ r 0 + AT 2 in the temperature range 12-30 K and r ¼ r 0 + BT À CT 3 in the temperature range 40-220 K. The M-H isotherm confirms the AFM nature of Nd 7 Pd 3 , which is confirmed further by the Arrott's plot.

Magnetostructural behavior in the non-centrosymmetric compound Nd7Pd3

“…Upon cooling, both of the smaller samples used in the physical property measurements order antiferromagnetically at TN = 37 K, followed by a ferromagnetic reordering via a very sharp first-order transition at TC = 33 K ( AC magnetic susceptibility measurement results ( Figure 3) are similar to those reported in Ref. [11]. They clearly show that the first magnetic transition in Nd7Pd3 on cooling occurs at 37 K, followed by the TC peak at 33 K, the anomaly at Tt = 16 K and another low temperature anomaly at Tf = 6 K. The latter transition is not seen in dc magnetization measurements but is prominent in the imaginary part of ac susceptibility.…”

“…. The observed net magnetic moment at 70 kOe is approximately 1.8 B per Nd atom, which is much lower than the gJJ value of 3.28 expected for Nd, and is in agreement with Refs [9,11]…”

“…Large magnetic anisotropy was reported, with a-axis as the easy and the c-axis as the hard magnetization directions. The same set of transitions at Tt = 15 K, TC = 34 K, and TN = 38 K was confirmed by AC magnetic susceptibility measurements at standard pressure [11]. For Nd7Pd3 and Sm7Pd3, large positive magnetovolume effects on cooling were observed below TC [8].…”

“…Authors of Ref. [11] ascribed the transition at Tf = 6 K to a spin-glass transition, arguing that it may potentially explain the magnetic hysteresis observed in the 2 K M(H) data.…”

“…The physical properties of this compound are sensitive to hydrostatic pressure, p: the FM state can be suppressed by p, and two different antiferromagnetic states, termed AFM1 and AFM2, emerge at the characteristic temperature Tt  10 K above 10 kbar. A recent study reported that dTC/dp and dTN/dp for Nd7Pd3 are, respectively, -1.906 K kbar -1 and -0.313 K kbar -1 , yet Tt is nearly independent of pressure [11]. Large magnetic anisotropy was reported, with a-axis as the easy and the c-axis as the hard magnetization directions.…”