Anomaly in the magnetocaloric effect in the intermetallic compoundDyAl2

Magnetic properties of single-crystalDyAl2

“…In this case, a negative MCE ͑i.e., ⌬S M Ͼ 0͒ is observed in the experimental data below 40 K, which becomes more positive with increasing field up to the maximum field of our apparatus ͑50 kOe͒. These results confirm the theoretical prediction of von Ranke et al 8 of a negative MCE along the ͓111͔ direction. However, their model predicts that the negative MCE has a maximum ͑positive͒ value at 10 kOe ͑ϳ2.7 J mol −1 K −1 ͒ and ϳ22 K, and then decreases with increasing field ϳ2.2 J mol −1 K −1 at 20 kOe and 21 K, and ϳ1.1 J mol −1 K −1 at 50 kOe and 19 K. In the mentioned theoretical work ͑Ref.…”

“…This compound has been extensively studied both theoretically and experimentally. 8,[10][11][12][13] At low temperature, the easy magnetization axis is the ͓100͔ direction, which changes to the ͓111͔ direction at ϳ40 K in zero magnetic field [10][11][12] or in an applied field of 57 kOe at 4 K. 10 A recent theoretical analysis 8 indicates that DyAl 2 should exhibit an anomaly in its ⌬S M vs. T curve, i.e., a negative MCE along the ͓111͔ direction below ϳ50 K. The anomaly was said to be associated with the change in the easy magnetization direction from the ͓100͔ to the ͓111͔. As reported by Levin et al, 14 the ac magnetic susceptibility of the polycrystalline DyAl 2 exhibits an anomaly at 42 K. In general, ac-susceptibility measurements are quite sensitive to detecting magnetic phase transitions initiated by a change of the magnetocrystalline anisotropy energy.…”

“…The CEF removes the degeneracy of the ground multiplet of the rare earth ion, which may lead to specific features of the magnetic properties such as an anomalous magnetocaloric effect. 8 Theoretical studies are also in progress in order to understand and to predict magnetic properties of new materials.…”

Magnetic and Magnetocaloric Properties of (Gd1-xCex)Al2(x = 0, 0.25, 0.5, 0.75) Compounds

“…Recent studies have verified that intermetallic RAl 2 (R = rare earth) compounds with cubic Laves-phase could be promising candidates for magnetic refrigeration technology due to their relatively large magnetic entropy change [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. Therefore, the magnetic and magnetocaloric properties of several intermetallic compounds, such as DyAl 2 [11,12], TbAl 2 [13], ErAl 2 [14], PrAl 2 [15][16][17] and GdAl 2 [18][19][20], and their alloys, such as Gd 1-x Pr x Al 2 [15], [18,25,26] and Gd-(Al 1-x Co x ) 2 [27], have recently been intensively investigated.…”

“…Therefore, the magnetic and magnetocaloric properties of several intermetallic compounds, such as DyAl 2 [11,12], TbAl 2 [13], ErAl 2 [14], PrAl 2 [15][16][17] and GdAl 2 [18][19][20], and their alloys, such as Gd 1-x Pr x Al 2 [15], [18,25,26] and Gd-(Al 1-x Co x ) 2 [27], have recently been intensively investigated. These recent studies have showed that the ground state for most intermetallic Laves compounds is ferromagnetic.…”