Publications associated with Correlated Electron Systems

Comparative study of the magnetic properties of La3Ni2B'O9 for B' = Nb, Ta or Sb

Journal of Solid State Chemistry Elsevier 258 (2017) 825-834

C-M Chin, P Battle, SJ Blundell, EC Hunter, F Lang, M Hendrickx, R Paria Sena, J Hadermann

<p>Polycrystalline samples of La<sub>3</sub>Ni<sub>2</sub>NbO<sub>9</sub> and La<sub>3</sub>Ni<sub>2</sub>TaO<sub>9</sub> have been characterised by X-ray and neutron diffraction, electron microscopy, magnetometry and muon spin relaxation (µSR); the latter technique was also applied to La<sub>3</sub>Ni<sub>2</sub>SbO<sub>9</sub>. On the length scale of a neutron diffraction experiment, the six-coordinate sites of the monoclinic perovskite structure are occupied in a 1:1 ordered manner by Ni and a random ⅓Ni/⅔B’ mixture. Electron microscopy demonstrated that this 1:1 ordering is maintained over microscopic distances, although diffuse scattering indicative of short-range ordering on the mixed site was observed. No magnetic Bragg scattering was observed in neutron diffraction patterns collected from La<sub>3</sub>Ni<sub>2</sub>B’O<sub>9 </sub>(B’ = Nb or Ta) at 5 K although in each case µSR identified the presence of static spins below 30 K. Magnetometry showed that La<sub>3</sub>Ni<sub>2</sub>NbO<sub>9</sub> behaves as a spin glass below 29 K but significant short-range interactions are present in La<sub>3</sub>Ni<sub>2</sub>TaO<sub>9</sub> below 85 K. The contrasting properties of these compounds are discussed in terms of their microstructure.</p>

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