Effect of uniaxial stress on helimagnetic phases in the square-lattice itinerant magnet EuAl${}_4$

Abstract

We investigate uniaxial-stress effects on the magnetic phase diagram of the square-lattice itinerant magnet EuAl${}_4$, where strong coupling among spin, lattice, and charge produces a variety of helimagnetic phases, including rhombic and square skyrmion lattices. Combining resistivity and magnetization measurements with neutron scattering, we find that compressive stresses of only several tens of megapascal along [010] enhance antiferromagnetic character and shorten the magnetic modulation period in the lowest-temperature single-Q spiral state, thereby driving the critical temperatures and fields of multiple phases to higher values. First-principles calculations show that increasing orthorhombic lattice distortion deforms the Fermi surface relevant to the magnetism, providing compelling evidence that Fermi-surface nesting plays a crucial role in stabilizing the helical magnetic modulations in EuAl${}_4$.

7 pages, 4 figures, SM: 2 pages, 2 figures. To be published in Physical Review B as a Letter