| Abstract: | Complex oxides have rich functionalities and advantages for future technologies. In many systems, quenched disorder often holds the key to determine their physical properties, and these properties can be further tuned by chemical doping. However,understanding the role of quenched disorder is complicated because chemical doping simultaneously alters other physical variables such as local lattice distortions and electronic and magnetic environments. Here, we show that spatial confinement is an effective approach to tuning the level of quenched disorder in a complex-oxide system while leaving other physical variables largely undisturbed. Through the confinement of a manganite system down to quasi-one-dimensional nanowires, we observed that the nature of its metal-insulator phase transition exhibits a crossover from a discontinuous to a continuous characteristic, in close accordance with quenched disorder theories. We argue that the quenched disorder, finite size, and surface effects all contribute to our experimental observations. Noticeably, with reduced nanowire width, the magnetoresistance shows substantial enhancement at low temperatures. Our findings offer new insight into experimentally tuning the quenched disorder effect to achieve novel functionalities at reduced dimensions. |
