Magnetotransport and Heat Capacity in Ternary Compounds U3M2M′3′, M=Al, Ga; M=Si, Ge

✍ Scribed by R. Troć; P. Rogl; V.H. Tran; A. Czopnik

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 416 KB
• Volume: 158
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2001.9096

✦ Synopsis

We report detailed studies of magnetization, electrical resistivity, magnetoresistivity, and heat capacity performed on the novel family of intermetallic compounds U 3 M 2 M 3 , (M ‫؍‬ Al, Ga, and M ‫؍‬ Si, Ge). The present measurements support the earlier conclusions about the ferrimagnetic properties of silicides and ferromagnetic properties of germanides. The resistivity for both compounds U 3 +Al, Ga, 2 Si 3 exhibits below T C a pronounced maximum observed for the 5rst time in an actinoid-ferrimagnet, probably caused by (a) the reduction of the number of e4ective conduction carriers or (b) a SDW-type of spin-disorder scattering of electrons. Both low-temperature resistivity (except for U 3 Ga 2 Si 3 ) and heat capacity may be described by a T-dependence involving a small gap on the order of 30+50 K in the magnon dispersion. The C p /T values at 2 K are enhanced and point to a medium+heavy fermion character of all these ternaries. Magnetoresistance for ferrimagnetic U 3 +Al, Ga, 2 Si 3 is rather small but positive in correspondence of antiferromagnetic interactions. In correspondence to the ferromagnetic materials, negative magnetoresistance is encountered for U 3 +Al, Ga, 2 Ge 3 . Speci5c features in the temperature dependence of magnetoresistivity / at various 5elds con5rm the sinusoidal modulation of the magnetic structure for U 3 Al 2 Ge 3 between 40 and 60 K. Also, such data for U 3 Ga 2 Ge 3 present strong indications for a similar magnetic modulation between 63 and 93 K, yet to be discovered by neutron di4raction experiments. In addition, the transition at 63 K is furthermore well resolved in the speci5c heat data of U 3 Ga 2 Ge 3 .