Structural and Physical Properties of CaFe4As3 Single Crystals

TL;DR

This study investigates the synthesis, structure, and physical properties of CaFe4As3 single crystals, revealing two phase transitions and complex magnetic and electrical behaviors related to antiferromagnetic order and first-order phase changes.

Contribution

It provides detailed experimental data on CaFe4As3's phase transitions, magnetic, electrical, and thermal properties, and discusses the ground state, which was not previously characterized.

Findings

Two successive phase transitions at 90 K and 26 K.

First-order phase transition indicated by thermal hysteresis.

Electrical resistivity follows T^α behavior with field-dependent constants.

Abstract

We report the synthesis, and structural and physical properties of CaFe4As3 single crystals. Needle-like single crystals of CaFe4As3 were grown out of Sn flux and the compound adopts an orthorhombic structure as determined by X-ray diffraction measurements. Electrical, magnetic, and thermal properties indicate that the system undergoes two successive phase transitions occurring at TN1 ~ 90 K and TN2 ~ 26 K. At TN1, electrical resistivities (\rho(b) and \rho(ac)) are enhanced while magnetic susceptibilities (\chi(b) and \chi(ac)) are reduced in both directions parallel and perpendicular to the b-axis, consistent with the scenario of antiferromagnetic spin-density-wave formation. At TN2, specific heat reveals a slope change, and \chi(ac) decreases sharply but \chi(b) has a clear jump before it decreases again with decreasing temperature. Remarkably, both \rho(b) and \rho(ac) decrease sharply with thermal hysteresis, indicating the first-order nature of the phase transition at TN2. At low temperatures, \rho(b) and \rho(ac) can be described by {\rho} = {\rho}0 + AT^\alpha ({\rho}0, A, and {\alpha} are constants). Interestingly, these constants vary with applied magnetic field. The ground state of CaFe4As3 is discussed.