Complex anisotropic magnetic phase diagram of EuGa₂Al₂

In many rare-earth based intermetallic compounds, the interplay between structural, magnetic and electronic properties gives rise to emergent, competing phenomena like unconventional superconductivity, heavy fermion behavior intermediate valence, and quantum criticality resulting in complex phase diagrams. Often the competing ground states can be tuned by magnetic field, pressure or chemical substitution. In this contributing, we study such emergent competition in EuGa₂Al₂ as a function of magnetic field and temperature. EuGa₂Al₂ is an isostructural compound to the tetragonal parent compounds EuX₄ (X = Ga, Al) where X is separated into two sublattices which can be preferentially occupied [1]. Eu exists in its magnetic 2⁺ state in EuGa₂Al₂ which orders antiferromagnetically at T_N ~ 20K, with multiple metamagnetic transitions below T_N and suspected charge order slightly above T_N [1]. We map out the high-resolution field – temperature phase diagram revealing a complex anisotropic behavior with many competing magnetic phases. Together with magneto-electrical transport, thermodynamic, and x-ray diffraction measurements, we discuss the correlations between its structural, magnetic and electronic properties that give rise to the complex phase diagram.
[1]Phys. Rev. B 97, 195146 (2018).