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The magnetocaloric effect of orthorhombic Gd(OH)CO3 has been experimentally studied, which exhibits −ΔSm up to 66.4 J kg−1 K−1 (355 mJ cm−3 K−1) for ΔH = 7 T and T = 1.8 K.

The results of a single-crystal X-ray-diffraction study of the evolution of crystal structures of VI3 with temperature with emphasis on phase transitions are presented. Some related specific-heat and magnetization data are included. The existence of the room-temperature trigonal crystal structure R-3 (148) has been confirmed. Upon cooling, VI3 undergoes a structural phase transition to a monoclinic phase at Ts ~ 79 K. Ts is reduced in magnetic fields applied along the trigonal c-axis. When VI3 becomes ferromagnetic at TFM1 ~ 50 K, magnetostriction-induced changes of the monoclinic-structure parameters are observed. Upon further cooling, the monoclinic structure transforms into a triclinic variant at 32 K which is most likely occurring in conjunction with the previously reported transformation of the ferromagnetic structure. The observed phenomena are preliminarily attributed to strong magnetoelastic interactions.

The magnetization and susceptibility of single-crystalline UCoAl were measured under high pressures to Pϭ1.2 GPa. A sharp metamagnetic transition was observed only in magnetic fields along the c axis. The critical field is B c ϭ0.65 T at Pϭ0 GPa, which increases with pressure and temperature. The susceptibility for ambient pressure shows a broad maximum at T max ϭ20 K. The value of T max increases with pressure. A theory of the itinerant metamagnetic transition has been generalized for the case of anisotropic spin fluctuations. The observed pressure dependence of the inverse susceptibility at T max , the temperature T 0 for the disappearance of the metamagnetic transition, and the temperature dependence of B c can be explained with this theory. ͓S0163-1829͑99͒04409-4͔

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