Fe-doping induced suppression of the second magnetic transition in S r4 R u3 O10

Ruthenium oxide (Sr4Ru3O10) exhibits a second magnetic transition at a temperature TM below its ferromagnetic (FM) transition (TC∼105 K), which has attracted considerable attention in the past two decades. Here, we successfully grew Sr4(Ru1-xFex)3O10 (x=0.01) crystal and systematically investigated the magnetotransport property of its nanosheets. We found a feature that there is an in-plane FM order aligned along 110directions below TC without the occurrence of the second magnetic transition at TM, which is in contrast to that expected in pure Sr4Ru3O10 nanosheets, where the in-plane FM order will rotate to the c direction below TM. Furthermore, a metamagnetic-like transition is also observed below ∼50 K at about 2 T when the magnetic field is applied along the c axis. These results unambiguously demonstrate that the second magnetic transition at TM is actually a consequence of spin reorientation induced by the inherent coupling between the spin and lattice, which can be effectively tuned by element doping.