Reentrant spin-glass and transport behavior of Gd4PtAl, a compound with three sites for Gd

Abstract

We report temperature (T) dependence (2-300 K) of DC and AC magnetization (M), isothermal remnant magnetization (MIRM), heat-capacity (C), electrical resistivity (ρ), and magnetoresistance (MR) of a ternary intermetallic compound, Gd4PtAl, crystallizing in a cubic (space group F4 3m) structure. In this structure, there are three sites for the rare-earth. The magnetization data reveal that, in addition to a magnetic transition at 64 K, there is another magnetic feature below 20 K. The C(T) data reveal an upturn below 64 K, shifting to a lower temperature with increasing field, which establishes that the onset of magnetic order is of an antiferromagnetic type. However, there is no worthwhile feature near 20 K in the C(T) curve. Ac susceptibility peak undergoes an observable change with frequency and, in particular the peak around 20 K gets suppressed with the application of a dc magnetic field; in addition, MIRM undergoes a slow decay with time and isothermal M exhibits low-field hysteresis below 20 K only, which are typical of spin-glasses. The results overall suggest that this compound is a reentrant spinglass in zero field. There are experimental signatures pointing to the existence of both antiferromagnetic and ferromagnetic components, competing with the variation of temperature and magnetic field, as a result of which electrical and magnetoresistance behaviors are peculiar. The results overall suggest that this compound exhibits interesting magnetic and transport properties.

Exploring the Different Degrees of Magnetic Disorder in TbxR1−xCu2 Nanoparticle Alloys

“…The latter is revealed by the positive value of the paramagnetic Curie temperature θ P ≈ 20 K (see Table 2). The presence of a disordered magnetic phase already at the bulk state has also been shown in other Gd intermetallics, such as in pollycrystalline Gd 4 PtAl [36] or GdCu 2 [15], where the obtained θ P ≈ 20 K agrees well with the one obtained in our Tb 0.5 Gd 0.5 Cu 2 bulk. For the NPs, a clear freezing transition T f takes place (at around 20 K), leading to the formation of a Super Spin Glass state (SSG) [37].…”

Giant Vertical Magnetization Shift Caused by Field-Induced Ferromagnetic Spin Reconfiguration in Ni50Mn36Ga14 Alloy

“…Moreover, the temperature dependence of the electrical resistivity is presented in Figure S4 . The resistivity shows an insulator behavior at higher temperatures, but around T P , an insulator-metal transition occurs, which may be ascribed to the effect of spin-disorder scattering of frozen spins in the magnetic inhomogeneous SG state [ 35 ].…”

“…The resistivity shows an insulator behavior at higher temperatures, but around TP, an insulator-metal transition occurs, which may be ascribed to the effect of spin-disorder scattering of frozen spins in the magnetic inhomogeneous SG state. [35] Figure 3a,b show the magnetic hysteresis (M-H) loops measured for the prepared Ni50Mn36Ga14 alloy after the ZFC and FC. The M-H loops were recorded at different temperatures and magnetic fields applied in the range from −0.5 kOe to +0.5 kOe after the ZFC and FC from 400 K. As shown in Figure 3a, VMS is not observed at ZFC.…”

Resistivity minimum in diluted metallic magnets

“…) For the parabolic dispersion, we can plug in the exact expression (11) into (19). Due to the r −2 asymptotic decay of the RKKY interaction J(r), the infinite sum in (19) The symbols show results obtained from SLL simulation, where the parameters are the same as in Fig. 6.…”

“…However, as it was pointed out by Doniach [3], the Kondo effect can be suppressed if the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction [4][5][6] becomes dominant. This work is motivated by an increasing number of materials that seem to belong to the RKKY dominated category yet still display a "Kondo-like" resistivity minimum [7][8][9][10][11][12][13][14][15][16][17][18][19][20], suggesting that the RKKY interaction can also produce a resistivity minimum under certain conditions.…”