Search for: All records

The solid solution LnSbxTe2−x−δ (Ln = lanthanide) is a family of square-net topological semimetals that exhibit tunable charge density wave (CDW) distortions and band filling dependent on x, offering broad opportunities to examine the interplay of topological electronic states, CDW, and magnetism. While several Ln series have been characterized, gaps in the literature remain, inviting a systematic survey of the remaining composition space that is synthetically accessible. We present our efforts to synthesize LnSbxTe2−x−δ across the remaining lanthanides via chemical vapor transport. Compiling our results with the reported literature, we generate a stability phase diagram across the ranges of Ln and x. We find a stability boundary for intermediate x beyond Tb, while x = 1 and x = 0 can be isolated up to Ho and Dy, respectively. SEM and XRD analyses of unsuccessful reactions indicated the formation of several stable binary phases. The presence of structurally related LnTe3 in samples suggests that stability is limited by the size of Ln, due to increasing compressive strain along the layer stacking axis with decreasing size. Finally, we demonstrate that late Ln can be stabilized in LnSbxTe2−x−δ via substitution into larger Ln members, synthesizing La1−yHoySbxTe2−x−δ as a proof of concept. 

Abstract 1D charge transport offers great insight into strongly correlated physics, such as Luttinger liquids, electronic instabilities, and superconductivity. Although 1D charge transport is observed in nanomaterials and quantum wires, examples in bulk crystalline solids remain elusive. In this work, it is demonstrated that spin‐orbit coupling (SOC) can act as a mechanism to induce quasi‐1D charge transport in the Ln₃MPn₅(Ln = lanthanide; M = transition metal; Pn = Pnictide) family. From three example compounds, La₃ZrSb₅, La₃ZrBi₅, and Sm₃ZrBi₅, density functional theory calculations with SOC included show a quasi‐1D Fermi surface in the bismuthide compounds, but an anisotropic 3D Fermi surface in the antimonide structure. By performing anisotropic charge transport measurements on La₃ZrSb₅, La₃ZrBi₅, and Sm₃ZrBi₅, it is demonstrated that SOC starkly affects their anisotropic resistivity ratios (ARR) at low temperatures, with an ARR of ≈4 in the antimonide compared to ≈9.5 and ≈22 (≈32 after magnetic ordering) in La₃ZrBi₅and Sm₃ZrBi₅, respectively. This report demonstrates the utility of spin‐orbit coupling to induce quasi‐low‐dimensional Fermi surfaces in anisotropic crystal structures, and provides a template for examining other systems. 

Colossal negative magnetoresistance is a well-known phenomenon, notably observed in hole-doped ferromagnetic manganites. It remains a major research topic due to its potential in technological applications. In contrast, topological semimetals show large but positive magnetoresistance, originated from the high-mobility charge carriers. Here, we show that in the highly electron-doped region, the Dirac semimetal CeSbTe demonstrates similar properties as the manganites. CeSb_0.11Te_1.90hosts multiple charge density wave modulation vectors and has a complex magnetic phase diagram. We confirm that this compound is an antiferromagnetic Dirac semimetal. Despite having a metallic Fermi surface, the electronic transport properties are semiconductor-like and deviate from known theoretical models. An external magnetic field induces a semiconductor metal–like transition, which results in a colossal negative magnetoresistance. Moreover, signatures of the coupling between the charge density wave and a spin modulation are observed in resistivity. This spin modulation also produces a giant anomalous Hall response.