Cluster Spin Glass Formation in the Double Double Perovskite CaMnFeTaO6

• Published in: Journal of physical chemistry. C Vol. 125; no. 17; pp. 9550 - 9555
• Main Authors: Kearins, Padraig, Solana-Madruga, Elena, Ji, Kunlang, Ritter, Clemens, Attfield, J. Paul
• Format: Journal Article
• Language: English
• Published: American Chemical Society 06.05.2021
• Subjects: C: Physical Properties of Materials and Interfaces
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.1c02172

CaMnFeTaO6 has been synthesized at 1200 °C under 10 GPa pressure. Powder neutron diffraction shows that CaMnFeTaO6 adopts a double double perovskite structure (tetragonal space group P42/n, lattice parameters a = 7.683(3) and c = 7.685(7) Å) with cation disorder at all transition-metal sites. Magnetization measurements reveal an apparent ferro- or ferrimagnetic transition at T m1 = 51 K and a susceptibility peak at T m2 = 20 K, but no long-range magnetic order is observed by neutron diffraction down to 1.5 K. This is attributed to the formation of superparamagnetic clusters of ferrimagnetically ordered spins below T m1 that freeze into a cluster spin glass at T f = T m2. ac magnetization measurements confirm the cluster spin glass ground state. Disorder from the substitution of Fe2+ for Mn2+ and Fe3+/Ta5+ inversion disrupts the network of superexchange interactions leading to the cluster spin glass ground state, in contrast to other P42/n double double perovskites where long-range magnetic order is stabilized.