Magnetic and magnetocaloric properties of partially disordered RFeAl (R = Gd, Tb) intermetallic

Magnetism and magnetocaloric effect in the ternary equiatomic REFeAl (RE = Er and Ho) compounds

“…Similar to that of GdFeAl and DyFeAl [16,18] evaluated to be 2.4, 6.1, and 8.3 J/kg K, and to be 3.4, 7.5, and 9.9 J/ kg K for RE ¼ Er and Ho with the magnetic field changes of 0e2, 0e5, and 0e7 T, respectively. These values are obviously larger than those for GdFeAl [16] and TbFeAl [17], and comparable with that DyFeAl [18]. with the field changes of 0e2 and 0e5 T for REFeAl (RE ¼ Er, Ho, Dy, Tb, and Gd) as well as some MCE materials are listed in Table 1 for comparison.…”

“…Dong et al [16] reported magnetic entropy change and refrigerant capacity in GdFeAl compound, the maximum magnetic entropy change and refrigerant capacity are found to be 3.7 J/kg K and 420 J/kg around T C~2 65 K for a field change of 5 T, respectively. The maximum magnetic entropy change for TbFeAl are found to be 3.3 J/kg K around 196 K for a field change of 4 T [17]. Very recently, Li et al [18] have studied the magnetic and MCE properties in DyFeAl.…”

Exchange bias-like effect in TbFeAl induced by atomic disorder

“…The magnetic phase transitions reported in the literature for TbFeAl [12,18,19] are reproduced in the magnetization curve, M (T ), obtained at 200 Oe which is presented in Fig 2. A bifurcation between the ZFC and FC arms is observed at ≈ 275 K (see inset (b)) followed by two humps at 186 K and at 145 K. The transition temperatures are determined by taking the derivative of M (T ) and is plotted as dM/dT in the inset (a). From this, T h c ≈ 198 K and T l c ≈ 154 K are determined.…”

“…Significant coercive field (H c ≈ 1.5 T) and magnetic saturation-like effects are observed at 2 K. The M (H) curves in Fig 3 (a) are comparable to the S-curve reported in TbFeAl. [9,11,12] Interestingly, sharp jumps of magnetization are observed in the zero field-cooled magneti- field cooled mode under different applied fields are presented. With the application of magnetic field, the hysteresis loops shift from the ZFC location though the displacement is not highly systematic.…”

“…Significantly high magnetocrystalline anisotropy leading to the formation of thin domain walls which are pinned to defects influences the magnetization, and to some extent, is the reason for the magnetocaloric effect. [12] Partial or total crystallographic disorder is a favourable ingredient for the observation of exchange bias. Granular * Electronic address: h.nair.kris@gmail.com, hsnair@uj.ac.za nanoparticles in a structurally and magnetically disordered matrix [13] or interacting magnetic defects embedded in an antiferromagnetic matrix with high degree of disorder [14] are example systems where disorder brings about exchange bias effect.…”