Ladder-like Structural Architecture of Layered Magnetic $A_{2.4}$Cr$_8$Te$_{14}$ ($A$ = Rb, Cs) Compounds by Self-flux Synthesis

TL;DR

This study reports the synthesis of a new family of layered magnetic alkali chromium tellurides with unique hybrid structures, revealing distinct magnetic ground states and demonstrating flux growth as an effective design strategy.

Contribution

The paper introduces a novel hybrid framework structure in alkali chromium tellurides synthesized via self-flux, with detailed magnetic characterization.

Findings

Rb₂.₄Cr₈Te₁₄ is antiferromagnetic with T_N = 114.5 K.

Cs₂.₄Cr₈Te₁₄ is ferrimagnetic with T_C = 125.0 K.

The structure combines features of delafossite and hollandite phases.

Abstract

The discovery and control of intergrowth structures represent an important avenue for the targeted synthesis of new, more complex structure types. When including magnetic framework metal atoms, this enhanced complexity can transfer to rich magnetic ground states. Here, we show that the subtle adjustment of the composition of alkali-tellurium fluxes enables the synthesis of a new family of alkali chromium tellurides, $A_{2.4}$Cr$_8$Te$_{14}$ ($A$ = Rb, Cs). Their ladder-like crystal structures integrate the two-dimensional character of delafossite-like $A$CrTe$_2$ with the tunnel motifs of hollandite-like $A_{x}$Cr$_5$Te$_8$ phases. This results in a previously unobserved unique hybrid framework. Direction-dependent magnetization measurements on oriented single crystals reveal distinct magnetic ground states: Rb$_{2.4}$Cr$_8$Te$_{14}$ is antiferromagnetic with $T_{\rm N}$ = 114.5 K, while Cs$_{2.4}$Cr$_8$Te$_{14}$ is ferrimagnetic with $T_{\rm C}$ = 125.0 K. This work underscores the simplicity and effectiveness of flux growth as a design strategy for discovering low-dimensional materials.