Magnetic and transport properties of single-crystal Yb3Cu4Ge4

Abstract The magnetic and transport properties of single-crystal Yb 3 Cu 4 Ge 4 with the Gd 3 Cu 4 Ge 4 -type orthorhombic structure are presented. Magnetization along the b -axis at 2 K saturates to 2.8 μ B / Yb at 3 kOe, while that along the a - and c -axes at 2 K are gradually increasing to the value of 1.5 μ B / Yb and 0.39 μ B / Yb at 50 kOe, respectively. The electrical resistivity within the ab -plane shows a metallic behavior in contrast to a broad maximum at around 30 K for that along the c -axis. Each resistivity for the principal axis suddenly decreases below 8 K. The specific heat shows a λ - type sharp peak at 7.8 K. The electronic specific heat coefficient is estimated to be 29.4 mJ/mol Yb K 2 by fitting the magnetic part of the specific heat below 3 K. The magnetic entropy released up to T C is 68% of that of R  ln 2, expected for the doublet ground state. It is revealed that Yb 3 Cu 4 Ge 4 is categorized to a weak heavy-fermion system showing a ferromagnetic transition at 7.8 K with uniaxial anisotropy along the b -axis.