  The magnetic ground state of double perovskite Sr2DyRuO6 has been
investigated using muon spin rotation and relaxation (muSR), neutron powder
diffraction (NPD) and inelastic neutron scattering (INS), in addition to heat
capacity and magnetic susceptibility (ac and dc) measurements. A clear
signature of a long-range ordered magnetic ground state has been observed in
the heat capacity data, which exhibit two sharp anomalies at 39.5 and 36 K
found as well in the magnetic data. Further confirmation of long-range magnetic
ordering comes from a sharp drop in the muon initial asymmetry and a peak in
the relaxation rate at 40 K, along with a weak anomaly near 36 K. Based on
temperature dependent NPD, the low temperature magnetic structure contains two
interpenetrating lattices of Dy and Ru5, forming an antiferromagnetic ground
state below 39.5 K with magnetic propagation vector k = (0,0,0). The magnetic
moments of Dy and Ru at 3.5 K are pointing along the crystallographic b-axis
with values of muDy = 4.92(10) muB and muRu = 1.94(7) muB, respectively. The
temperature dependence of the Ru moments follows a mean field type behaviour,
while that of the Dy moments exhibits a deviation indicating that the primary
magnetic ordering is induced by the order of the 4d electrons of Ru rather than
that of its proper 4f Dy electrons. The origin of the second anomaly observed
in the heat capacity data at 36.5 K must be connected to a very small spin
reorientation as the NPD studies do not reveal any clear change in the observed
magnetic Bragg peaks positions or intensities between these two transitions.
INS measurements reveal the presence of crystal field excitations (CEF) in the
paramagnetic state with overall CEF splitting of 73.8 meV, in agreement with
the point change model calculations.
