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K. Kutko, B. Bernáth, O. Wiedmann, O. Young, H. Engelkamp, P. Christianen, V. Poperezhai, L. Pourovskii, S. Khmelevskyi, D. Kamenskyi:
"Massive Magnetostriction of the Paramagnetic Insulator KEr(MoO4)2 via a Single‐Ion Effect.";
Advanced Electronic Materials, 2100770 (2021).

The magnetostriction phenomenon, which exists in almost all magnetically
ordered materials, is proved to have wide application potential in precision
machinery, microdisplacement control, robotics, and other high-tech fields.
Understanding the microscopic mechanism behind the magnetostrictive
properties of magnetically ordered compounds plays an essential role in real-
izing technological applications and helps the fundamental understanding
of magnetism and superconductivity. In paramagnets, however, the magne-
tostriction is usually significantly smaller because of the magnetic disorder.
Here, the observation of a remarkably strong magnetostrictive response of
the insulator paramagnet KEr(MoO4)2 is reported on. Using low-temperature
magnetization and dilatometry measurements, in combination with ab initio
calculations, employing a quasi-atomic treatment of many-body effects, it is
demonstrated that the magnetostriction anomaly in KEr(MoO4)2 is driven
by a single-ion effect. This analysis reveals a strong coupling between the
Er3+ ions and the crystal lattice due to the peculiar behavior of the magnetic
quadrupolar moments of Er3+ ions in the applied field, shedding light on the
microscopic mechanism behind the massive magnetostrictive response.

https://publik.tuwien.ac.at/files/publik_302156.pdf