Stoichiometry and Phase Control in K$_{1-x}$CrSe$_2$ via Self-Flux Synthesis

TL;DR

This study demonstrates how quenching temperature influences phase formation, stoichiometry, and magnetic properties in K$_{1-x}$CrSe$_2$, a layered magnetic material, by controlling synthesis conditions and enabling detailed magnetic measurements.

Contribution

It reveals the relationship between synthesis parameters, phase stability, and magnetic behavior in K$_{1-x}$CrSe$_2$, providing new insights into controlling delafossite-type magnetic materials.

Findings

Identified three distinct K$_{1-x}$CrSe$_2$ phases with different structures.

Successfully grew single crystals of full-stoichiometric KCrSe$_2$.

Observed field-dependent Néel temperature and weak metamagnetic transition.

Abstract

Layered delafossite-type magnetic materials, such as KCrSe$_2$, are promising platforms for studying magnetic systems and potential frustration on triangular lattices. Synthesis, structure-type control, and off-stoichiometries remain major challenges in the investigation of these delafossite-type magnets. Starting from the same self-flux composition (K:Cr:Se = 8:1:8), we isolated three distinct K$_{1-x}$CrSe$_2$ phases with $x$ = 0, 0.13--0.17, and 0.32--0.35, each adopting a different structure type depending on the quenching temperature applied. The phase evolution indicates a sequence of transformations during synthesis between compounds with varying degrees of potassium deficiency. Building on these insights into phase stability and crystal growth, we successfully grew single crystals of full-stoichiometric KCrSe$_2$ -- enabling direction-dependent magnetization measurements. These measurements reveal a pronounced field dependence of the N\'{e}el temperature at low external fields, as well as a weak metamagnetic transition. Our findings demonstrate that even a simple parameter -- such as quenching temperature -- can be used to control stoichiometry, direct phase formation, and ultimately tune the magnetic properties of delafossite-type materials.