Crystal Structure and Magnetic Properties of the Trilayered Perovskite Sr4Rh3O10: A New Member of the Strontium Rhodate Family

The trilayered perovskite Sr4Rh3O10 is reported for the first time. High-pressure and high-temperature heating (6 GPa and 1500°C) brought about successful preparation of a polycrystalline sample of the expected member at n = 3 of Srn+1RhnO3n+1. Neutron-diffraction studies revealed the orthorhombic crystal structure (Pbam) at room temperature and 3.4 K. Local structure distortions rotationally tilt the RhO6 octahedra ~12° in the perovskite-based blocks along the c-axis, and approximately a 20% disorder was found in the sequence of the alternating rotational tilt. The sample was also investigated by measurements of specific heat, thermopower, magnetic susceptibility, and electrical resistivity. The data clearly revealed enhanced paramagnetism and electrically conducting character, which reflected the nature of the correlated 4d^5-electrons of Rh^4+. However, no clear signs of magnetic and electrical transitions were observed above 2 K and below 70 kOe, providing a remarkable contrast to the rich electronic phenomena for the significantly relevant ruthenate Sr4Ru3O10.