Magnetism and Correlated Electrons in LaCr${}_2$Ge${}_2$N

Abstract

We report the synthesis, structure and physical properties of a new quaternary nitride LaCr${}_2$Ge${}_2$N. The compound crystallizes in the CeCr${}_2$Si${}_2$C-type structure (P4/mmm), featuring distinctive Cr${}_2$N square sheets within Cr${}_2$Ge${}_2$N block layers. Physical characterizations reveal enhanced electron correlations evidenced by a Sommerfeld coefficient substantially larger than band calculations and pressure-induced deviation from Fermi-liquid behavior. Magnetic measurements show short-range antiferromagnetic correlations developing around 460 K, followed by long-range magnetic ordering at 14 K. Additionally, subtle anomalies at 378 K suggest possible electronic ordering. First-principles calculations reveal nearly-flat Cr-3d bands near the Fermi level and predict a striped antiferromagnetic ground state. This work demonstrates how electron count variation in the CeCr${}_2$Si${}_2$C-type structure family leads to magnetic ordering in LaCr${}_2$Ge${}_2$N, contrasting with the paramagnetic behavior of LnCr${}_2$Si${}_2$C compounds.

8 pages, 5 figures, 3 tables. Accepted for publication in Physical Review B

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