We studied the ferrimagnet ${\mathrm{La}}_5{\mathrm{Mo}}_4{\mathrm{O}}_{16}$ with Mo ions on quasisquare lattices both experimentally and theoretically. We found that in addition to the antiferromagnetic ordering at $T_N=200$ K, a magnetic phase transition into a ferrimagnetic phase occurs at $T_{s1}=60$ K, which is caused by the orbital ordering of the Mo $4d$ states. We also found that the relatively small size of ferrimagnetic domains despite the large Ising anisotropy of the Mo spins are formed below $T_{s1}$, which are responsible for the relaxation behavior and the memory effect in the magnetization. Nonvolatile positive magnetoresistance observed in this compound below $T_{s1}$ can be attributed to the fact that such magnetic domains and the electrical conduction along the domain walls disappear with the applied magnetic field.

• Received 14 July 2020
• Revised 11 November 2020
• Accepted 6 January 2021

DOI:https://doi.org/10.1103/PhysRevResearch.3.013105

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Published by the American Physical Society