Investigation of the Magnetic Field Dependence of the Strongly Correlated Electron System, SrRu\(_2\)O\(_6\)

Ruthenate systems have attracted a large amount of attention due to the interesting physical phenomena that can manifest as a result of the competition between fundamental interactions arising from the 4\(d\) electrons in the Ru ions. This is exemplified by systems such as Sr\(_2\)RuO\(_4\), a layered perovskite which exhibits superconductivity at a critical temperature, \(T\)\(_c\) ≈ 1 K and Sr\(_3\)Ru\(_2\)O\(_7\), an itinerant metamagnet which has been shown to contain spin density waves. Hence ruthenates prove to be promising materials to produce and explore new physics which could lead to new innovative technologies.

More recently the ruthenate, SrRu\(-2\)O\(_6\) has been synthesised and shown to have an unusually high antiferromagnetic ordering temperature, \(T\)\(_N\) = 565 K. While the physical properties of SrRu\(_2\)O\(_6\) have been studied by several groups, no field dependent studies have yet been reported in the literature. As such the main aim of the research discussed within this thesis was to conduct the first magnetic field dependent study on SrRu\(_2\)O\(_6\).

The structural and magnetic properties were investigated in applied magnetic fields ranging from 0.1 to 7 T, using neutron powder diffraction and DC susceptibility measurements, over a range of temperatures from 1 to 150 K. The hexagonal layered structure of SrRu2O6 and its antiferromagnetic order were found to remain constant over both the temperatures and fields studied. With the magnetic moment of the Ru ions being found to have a value of 1.465(18) µB. In addition to the previously reported anisotropic thermal expansion a positive magnetostriction in the order of ̴ x10\(^{-5}\) Å was observed, over the temperatures and fields studied, suggesting that there are large amounts of magnetoelastic coupling between intralayer Ru\(^{5+}\) ions. This is expected to originate from the dominant superexchange interaction mediated by the O ions.