Influence of structural distortions on the magnetic order of rare-earth titanates*

Perovskite oxides feature fundamentally and technologically alluring properties such as magnetism, superconductivity and colossal magnetoresistance. How structural distortions and disorder influence the electron system in these materials is an important open question. Rare-earth titanates show promise in shedding new light on this problem through the study of their magnetic ground states, which are controlled by distortions induced by different-sized rare-earth ions. The compounds exhibit an interplay among charge, orbital, spin and lattice degrees of freedom, which produces a complex phase diagram that includes ferromagnetic and antiferromagnetic phases (e.g., in Y_1-xLa_xTiO₃) and metal-insulator transitions (e.g., Y_1-xCa_xTiO₃, La_1-xSr_xTiO₃). We have conducted NMR measurements on select rare-earth titanates. Our results point to unusual local behavior well above magnetic ordering temperatures, which is not seen by macroscopic probes. Additionally, we have modified the structural distortions by uniaxial pressure and investigated their effect via magnetic susceptibility measurements.