Magnetic order in Pr2Pd3Ge5 and possible heavy-fermion behavior in Pr2Rh3Ge5

We report our results on two ternary intermetallic compounds Pr2Pd3Ge5 and Pr2Rh3Ge5 based on magnetic susceptibility, magnetization, specific heat, resistivity, and magnetoresistance data. These compounds form in U2Co3Si5-type orthorhombic structure (space group Ibam). Pr2Pd3Ge5 exhibits two magnetic transitions at T-N1 = 7.5 K and T-N2 = 8.3 K. In the magnetically ordered state, Pr2Pd3Ge5 exhibits a field-induced metamagnetic transition and unusually large magnetoresistance. Pr2Rh3Ge5 does not show any phase transition down to 0.5 K. It has a crystal electric field singlet ground state, separated from the first excited state by about 10 K. The low lying crystal field excitations lead to exciton mediated electronic mass enhancement, as evidenced by a large Sommerfeld coefficient (gamma similar to 80 mJ/mol K-2) in Pr2Rh3Ge5.