Competition of three-dimensional magnetic phases in Ca$_2$Ru$_{1-x}$Fe$_x$O$_4$: A structural perspective
ORAL
Abstract
The crystalline and magnetic structures of Ca$_2$Ru$_{1-x}$Fe$_x$O$_4$ have been studied using neutron and X-ray diffraction. The Fe-doping reduces the Ru-O bond length in both apical and planar directions. The smaller Ru(Fe)O$_6$ octahedron leads to its reduced distortion. The $Pbca$ space group is maintained in all the Fe-dopings, so is the octahedral flattening. Two competing antiferromagnetic orders, $A$- and $B$-centered phases have been observed. The Fe-doping-relaxed crystal structure prefers the latter to the former. The absence of the two-dimensional antiferromagnetic critical fluctuations above the magnetic transition temperature and the three-dimensional magnetic correlation below the transition, together with the anomalous lattice response, point to an important role of orbital degree of freedom in driving the magnetic phase competition.
*This research used resources at the High Flux Isotope Reactor, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory, and was supported in part by the US Department of Energy, Office of Science, Office of Basic Energy Sciences. GC acknowledges support by the National Science Foundation via grant DMR-1903888.
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Presenters
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Songxue Chi
- Oak Ridge National Lab
- Oak Ridge National Laboratory