Observation of Magnetic Memory Effect and Photo-induced Magnetism in Y$_{0.33}$Sr$_{0.67}$CoO$_{3-\delta}$

We prepared the Y$_{0.33}$Sr$_{0.67}$CoO$_{3-\delta }$by the conventional solid state method which sintered under the O$_{2}$ flow. The sample was finally annealed under the oxygen and nitrogen atmosphere. A DC magnetization jump was found about 200 K with a large thermal hysteresis at 0.01 T indicating a kind of magnetic memory effect. The magnetization jump comes from the inter-spin state transition on Co$^{3+}$ ion from low to intermediate spin state. The magnetic memory effect gradually disappears with the magnetic field increase and the jump temperature ($T_{J})$ shifts to low temperature. Annealed samples indicate high $T_{J}$, $T_{C}$ and the magnetization coming from the oxygen content difference. Under the irradiation of a pulsed near-infrared laser ($\lambda $ = 1050 nm), the $T_{J}$ shifts to low temperature and the magnetization below T$_{J}$ decreases. Photo-induced effect is weakened with the magnetic field. Laser irradiation may suppress spin-state transition of the part Co$^{3+}$ ions.