Thermodynamic insights into the intricate magnetic phase diagram of EuAl${}_4$

Abstract

The tetragonal intermetallic compound EuAl${}_4$ hosts an exciting variety of low temperature phases. In addition to a charge density wave below 140 K, four ordered magnetic phases are observed below 15.4 K. Recently, a skyrmion phase was proposed based on Hall effect measurements under a $c$-axis magnetic field. We present a detailed investigation of the phase transitions in EuAl${}_4$ under $c$-axis magnetic field. Our dilatometry, heat capacity, DC magnetometry, AC magnetic susceptibility, and resonant ultrasound spectroscopy measurements reveal three magnetic phase transitions not previously reported. We discuss what our results reveal about the character of the magnetic phases. Our first key result is a detailed $H\parallel [001]$ magnetic phase diagram mapping the seven phases we observe. Second, we identify a new high-field phase, phase VII, which directly corresponds to the region were skyrmions have been suggested. Our results provide guidance for future studies exploring the complex magnetic interactions and spin structures in EuAl${}_4$.

20 pages, 15 figures

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Cited by in corpus (19)

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• Origin of Charge Density Wave in Topological Semimetals SrAl4 and EuAl4
• Non-centrosymmetric, transverse structural modulation in SrAl4, and elucidation of its origin in the BaAl4 family of compounds
• Resonant elastic X-ray scattering of antiferromagnetic superstructures in EuPtSi${}_3$
• Real-space Visualization of Charge Density Wave Induced Local Inversion-Symmetry Breaking in a Skyrmion Magnet
• Experimental progress in Eu(Al,Ga)${}_4$ topological antiferromagnets
• Magnetic bubble crystal in tetragonal magnets
• Anisotropic skyrmion crystal on a centrosymmetric square lattice under an in-plane magnetic field
• A Magnon Band Analysis of GdRu2Si2 in the Field-Polarized State
• Enhanced Phonon-Phonon Interactions and Weakened Electron-Phonon Coupling in Charge-Density-Wave Topological Semimetal EuAl4 with a Possible Intermediate Electronic State
• Chern insulating state with double-$Q$ ordering wave vectors at the Brillouin zone boundary
• Incommensurate Transverse Peierls Transition
• Band structure and charge ordering of Dirac semimetal EuAl${}_4$ at low temperatures
• Correlation between Complex Spin Textures and the Magnetocaloric and Hall Effects in Eu(Ga${}_{1-x}$Al${}_x$)${}_4$ ($x$ = 0.9, 1)
• I-centered vs F-centered orthorhombic symmetry and negative thermal expansion of the charge density wave of EuAl2Ga2
• Electron-phonon coupling in EuAl4 under hydrostatic pressure
• Square skyrmion lattice in multiorbital $f$-electron systems