SPICE Workshop on Unconventional Superconductors and Magnets May 12th - 14th, 2026
Emilia Moorosan
Square-net lattice materials are known for hosting diverse and intriguing physical properties, from real and reciprocal-space topology to unique electronic behaviors protected by symmetry. These properties are achieved even without geometric frustration or anisotropic interactions, making them attractive candidates for studying unconventional magnetic states. In this talk, I will discuss the physics of a metallic, square-net lattice rare earth compound EuRhAl4Si2. This is an antiferromagnet below TN = 11.4 K, with RKKY interactions leading to magnetic frustration. The effective exchange interactions compete with the uniaxial anisotropy resulting in a rare ferrimagnetic “up-up-down” phase. As a result, the magnetization in the AFM state displays a 1/3 step (M), associated with the “up-up-down” moment configuration. More importantly, we find two additional much smaller steps (“-/+m”) at the 1/3M plateau, where m is a small induced moment (m<<M). These can be understood in a scenario where, applying a magnetic field, atomically sharp solitons are precipitated, having all the foundational credentials for a racetrack memory at the spatial limit [1].
The experimental evidence from field-dependent magnetization and magnetoresistance measurements is corroborated by DFT calculations relating the RKKY interaction and the magnetic anisotropy to the electronic structure. We performed atomistic spin-dynamics calculations relating the interaction parameters to the 1D magnetic soliton formation.
[1] K. Allen, K. Du, J. Bouaziz, S. Mishra, G. Bihlmayer, Y. Zhang, Y. Hao, V. Ukleev, C. Luo, F. Radu, Y. Gao, Ch. Lane, J.-X. Zhu, M. Yi, H. Cao, S.-W. Cheong, S. Blügel, and E. Morosan, Nature Physics (under review)