The compound TiOCl is a quasi-1-dimensional (1D) quantum magnet (Seidel et al., 2003). Upon cooling, TiOCl undergoes a phase transition at Tc2 = 90 K towards a state with incommensurate magnetic order, followed by a second phase transition at Tc1 = 67 K towards a spin-Peierls state (Seidel et al., 2003; Shaz et al., 2005; van Smaalen et al., 2005). Both low-temperature phases involve structural distortions that have been characterized by x-ray diffraction. The absence of any phase transitions has been reported for scandium-doped TiOCl with doping levels 0.01 < x < 0.1 for ScxTi1-xOCl (Glancy et al., 2008(Glancy et al., , 2010 Zhang et al., 2010; Aczel et al., 2011). We have synthesized ScxTi1-xOCl for x = 0.005. Based on temperature-dependent x-ray diffraction experiments and specifichear measurements, we have found that the x = 0.005 compound transforms into incommensurate and spin-Peierls-like phases on cooling. Despite apparent large correlation lengths, these phases lack long-range order. A sluggish transformation is thus found between states of ScxTi1-xOCl that support different kinds of fluctuations.

Temperature-dependent electronic and magnetic properties are reported for nickel-deficient NiV 2 Se 4 . Single-crystal X-ray diffraction shows it to crystallize in the monoclinic Cr 3 S 4 structure type with space group I2∕m and vacancies on the Ni site, resulting in the composition Ni 0.85 V 2 Se 4 in agreement with our electron-probe microanalysis. Structural distortions are not observed down to 1.5 K. Nevertheless, the electrical resistivity shows metallic behavior with a broad anomaly around 150-200 K that is also observed in the heat capacity data. This anomaly indicates a change of state of the material below 150 K. It is believed that this anomaly could be due to spin fluctuations or charge-density-wave fluctuations, where the lack of long-range order is caused by vacancies at the Ni site of Ni 0.85 V 2 Se 4 . The non-linear temperature dependence of the resistivity as well as an enhanced value of the Sommerfeld coefficient 𝜸 = 104.0 (1) mJ mol −1 K −2 suggest strong electron-electron correlations in this material. First-principles calculations performed for NiV 2 Se 4 , which are also applicable to Ni 0.85 V 2 Se 4 , classify this material as a topological metal with Z 2 = (1; 110) and coexisting electron and hole pockets at the Fermi level. The phonon spectrum lacks any soft phonon mode, consistent with the absence of periodic lattice distortion in the present experiments.