Magnetotunneling Experiments Using La$\text{}_{0.7}$Sr$\text{}_{0.3}$MnO$\text{}_{3}$ Based Break Junctions

The La$\text{}_{0.7}$Sr$\text{}_{0.3}$MnO$\text{}_{3}$ perovskite is a ferromagnetic half-metal with a strong spin polarization and high Curie temperature T$\text{}_{C}$ (355K). We have shown that a combination of the break junction technique with the special properties of the La$\text{}_{0.7}$S$\text{}r_{0.3}$MnO$\text{}_{3}$ perovskite can lead to extremely high values of tunneling magnetoresistance ratio (> 10$\text{}^{3}$%) and high field sensitivity (30%/Oe). These results are obtained in magnetic fields below 1kOe and at room temperature.