Single-Ion Anisotropy in Lattice-Disordered Quasi-1D Transverse Ising System CoNb$_{\mathrm{2}}$O$_{\mathrm{6}}$

Historically, the ability to probe the non-equilibrium properties of bulk quantum magnets has been largely stifled by the extremely short (picosecond) relaxation timescales displayed by these systems. In the well-known quasi-1D Transverse Field Ising system CoNb$_{\mathrm{2}}$O$_{\mathrm{6}}$, relaxation times have been observed to increase by several orders of magnitude at low temperatures and fields. This long relaxation time leaves the material -- and its non-equilibrium phase diagram -- open to previously inaccessible experimental techniques such as neutron scattering. The mechanisms of this slow magnetic relaxation remain unclear, but could be resolved by investigating the single-ion effects occurring at the magnetic Co$^{\mathrm{2+}}$ sites in the crystal lattice. To accomplish this, Co$^{\mathrm{2+}}$ doped into non-magnetic columbite MgNb$_{\mathrm{2}}$O$_{\mathrm{6}}$ in an effort investigate these effects through the diluted Ising chains. Powder samples of Mg$_{\mathrm{1-x}}$Co$_{\mathrm{x}}$Nb$_{\mathrm{2}}$O$_{\mathrm{6}}$ (with x $=$ 0.01, 0.05, 0.1, 0.2) were synthesized using a sintering technique, and single-ion anisotropic interactions were explored via electron paramagnetic resonance (EPR) and AC susceptibility measurements on the lattice-disordered variant.