Weak ferromagnetism and spin-charge coupling in single-crystal Sr2YRuO6 -: art. no. 184432

Sr2YRuO6 is a magnetic insulator with a double-perovskite structure derived from the perovskite SrRuO3, which is an itinerant ferromagnet. Measurements of the magnetic susceptibility, magnetization, and electrical resistivity are performed on newly synthesized single crystals of Sr2YRuO6. The system orders antiferromagnetically at T-N = 26 K and yet shows a conspicuous occurrence of weak ferromagnetism characterized by large irreversibility in both magnetic susceptibility and isothermal magnetization. The ordered magnetic moment at 7 T shows weak temperature dependence and is only 0.5 mu (B)/Ru, substantially low compared to that expected for an S = 3/2 system, consistent with weak ferromagnetism. The electrical resistivity demonstrates a weak temperature dependence from 800 to 160 K and a rapid rise in the lower-temperature range. A sharp anomaly in the resistivity is observed at the magnetic ordering temperature T-N, which is then followed by a Mott-like transition at T-M = 17 K. The system also exhibits sizable negative magnetoresistance, which persists well above the magnetic ordering temperature. All results presented reveal unusual magnetic and transport properties that underscore the strong interplay of spin, charge, and orbital degrees of freedom.