Tetragonal Kondo Insulator EuCd_2Sb_2 Discovered via High Pressure High Temperature Synthesis

摘要

Magnetic and electronic properties of quantum materials heavily rely on thecrystal structure even in the same chemical compositions. In this study, it isdemonstrated that a layered tetragonal EuCd_2Sb_2 structure can be obtained bytreating bulk trigonal EuCd_2Sb_2 under high pressure (6 GPa) and hightemperature (600 ℃). Magnetization measurements of the newly formedlayered tetragonal EuCd_2Sb_2 confirm an antiferromagnetic ordering with Neeltemperature (T_N) around 16 K, which is significantly higher than that(T_N ≈ 7 K) of trigonal EuCd_2Sb_2, consistent with heat capacity measurements.Moreover, bad metal behavior is observed in the temperature dependence ofthe electrical resistivity and the resistivity shows a dramatic increase aroundthe Neel temperature. Electronic structure calculations with local densityapproximation dynamic mean–field theory (LDA+DMFT) show that thismaterial is strongly correlated with well-formed large magnetic moments, dueto Hund’s coupling, which is known to dramatically suppress the Kondo scale.