Recent advances in understanding and manipulating magnetic and electronic properties of EuM₂X₂(M= Zn, Cd;X= P, As)

Over the past five years, significant progress has been made in understanding the magnetism and electronic properties of CaAl₂Si₂-type EuM₂X₂(M= Zn, Cd;X= P, As) compounds. Prior theoretical work and experimental studies suggested that EuCd₂As₂had the potential to host rich topological phases, particularly an ideal magnetic Weyl semimetal state when the spins are polarized along thecaxis. However, this perspective is challenged by recent experiments utilizing samples featuring ultra-low carrier densities, as well as meticulous calculations employing various approaches. Nonetheless, the EuM₂X₂family still exhibit numerous novel properties that remain to be satisfactorily explained, such as the giant nonlinear anomalous Hall effect and the colossal magnetoresistance effect. Moreover, EuM₂X₂compounds can be transformed from semiconducting antiferromagnets to metallic ferromagnets by introducing a small number of carriers or applying external pressure, and a further increase in the ferromagnetic transition temperature can be achieved by reducing the unit cell volume. These features make the EuM₂X₂family a fertile platform for studying the interplay between magnetism and charge transport, and an excellent candidate for applications in spintronics. This paper presents a comprehensive review of the magnetic and transport behaviors of EuM₂X₂compounds with varying carrier densities, as well as the current insights into these characteristics. An outlook for future research opportunities is also provided.