Ferromagnetic Ground States with High Transition Temperatures in New Tetragonal Rare-Earth Compounds CeRu2Al2B and PrRu2Al2B

We report on the discovery of ferromagnetic ground states in the newly synthesized tetragonal compounds CeRu 2 Al 2 B and PrRu 2 Al 2 B. Polycrystalline samples of these compounds were synthesized and their magnetization M ( B ) and electrical resistivity ρ( T ) were measured as functions of the magnetic field B and the temperature T . CeRu 2 Al 2 B is a metallic compound with trivalent Ce ions and is classified into a Kondo-lattice system: a Kondo-like -ln T dependence of ρ( T ) is observed below 32 K. The cusp at T N Ce = 14.3 K and the steep increase at approximately T C Ce = 13 K observed in the magnetic susceptibility M / B ( T ) correspond to antiferromagnetic (AFM) and ferromagnetic (FM) transitions, respectively. T C Ce is the second highest transition temperature of the Ce-based ferromagnet with no other magnetic elements. PrRu 2 Al 2 B is also a metallic compound with trivalent Pr ions. The M / B ( T ) of PrRu 2 Al 2 B shows a cusp at T N Pr = 26 K and a steep increase at approximately T C Pr = ...