Spin and Charge Density Waves and Stripes in Trilayer Nickelates

Spin and charge ordering occurs in nickelates as stripes and density waves. Here, I will discuss results from a series of neutron and X-ray single-crystal scattering experiments on trilayer nickelates. First, I discuss the spin and charge stripes in the T' trilayer nickelate, La4Ni3O8, which are associated with its semiconductor-insulator transition. Second, I will discuss strongly coupled spin and charge density waves that occur under ambient pressure in trilayer Ruddlesden-Popper R4Ni3O10 crystals.