Pressure-induced switching of electronic nematicity in the iron-based ladder materials ${\mathrm{BaFe}}_2({\mathrm{S}}_{1\text{−}x}{\mathrm{Se}}_x{)}_3$ $(x=0–1)$

We examined a pressure dependence of an electronic nematicity in iron-based ladder materials ${\mathrm{BaFe}}_2{\left({\mathrm{S}}_{1\text{−}x}{\mathrm{Se}}_x\right)}_3$ with a quasi-one-dimensional ladder lattice by tracking an anomaly in the resistivity. For $x=0$, the ferroic nematicity observed at ambient pressure is stabilized by applying pressure up to 2 GPa. For $x=0.25$, 0.60, and 1, the antiferroic nematicity at ambient pressure switches into ferroic nematicity by applying pressures of 0.50–4.0 GPa. We present the electronic phase diagram of ${\mathrm{BaFe}}_2{\left({\mathrm{S}}_{1-x}{\mathrm{Se}}_x\right)}_3$ in terms of the lattice parameters, and discuss the relationship between the nematicity and bandwidth. We also discuss that the external pressure causes a filling control through the charge transfer from anions to cations in the Se-rich compositions.

Figure 1

(a) A schematic illustration of the crystal structure of ${\mathrm{BaFe}}_2{X}_3$ with $Pnma$ space group depicted by vesta [14]. (b) Temperature dependencies of electrical resistivity ($\rho$) and its temperature ($T$) derivative ($dlog\rho /dT$) for ${\mathrm{BaFe}}_2{\mathrm{S}}_3$ and ${\mathrm{BaFe}}_2{\mathrm{Se}}_3$ at ambient pressure. The data in (b) are taken from Ref. [15]. Schematic illustrations of (c) orbital and (d) magnetic order.

Figure 2

Temperature dependencies of electrical resistivity ($\rho$) and its temperature ($T$) derivative ($dlog\rho /dT$) at various pressures of ${\mathrm{BaFe}}_2{\left({\mathrm{S}}_{1-x}{\mathrm{Se}}_x\right)}_3$ for (a), (e) $x=0$, (b), (f) $x=0.25$, (c), (g) $x=0.60$, and (d), (h) $x=1$. The $dlog\rho /dT$ are vertically shifted for clarity. The insets of (d) and (f) show the high-temperature parts of $dlog\rho /dT$. The ferroic and antiferroic nematicity temperatures ($T_{\mathrm{F}}^{★}$ and $T_{\mathrm{AF}}^{★}$) and Néel temperature ($T_{\mathrm{N}}$) are indicated by diamonds, triangles, and circles, respectively. Results for $x=1$, 0.25, and 0.60 were measured in the piston cylinder (PC) and $x=1$ in the diamond anvil cell (DAC), respectively. See the main text for details.

Figure 3

Temperature ($T$) dependencies of electrical resistivity ($\rho$) and its temperature derivative of $x=1$ for ${\mathrm{BaFe}}_2{\left({\mathrm{S}}_{1-x}{\mathrm{Se}}_x\right)}_3$.

Figure 4

Temperature dependence of electrical resistivity ($\rho$) of $x=1$ for ${\mathrm{BaFe}}_2{\left({\mathrm{S}}_{1-x}{\mathrm{Se}}_x\right)}_3$ under high pressure measured using a cubic anvil cell (CAC).

Figure 5

Electronic phase diagram in the temperature-pressure plane for ${\mathrm{BaFe}}_2{\left({\mathrm{S}}_{1-x}{\mathrm{Se}}_x\right)}_3$, (a) $x=0$, (b) $x=0.25$, (c) $x=0.60$, and (d) $x=1$. The transition temperatures are determined by analyzing the data collected using PC for $x=0$, 0.25, and 0.60, and DAC for $x=1.0$. The $T_{\mathrm{F}}^{★}$ and $T_{\mathrm{AF}}^{★}$ represent the transition temperatures of ferroic nematicity (F-Nem) and antiferroic nematicity (AF-Nem), respectively. The $T_{\mathrm{N}}$ is the antiferromagnetic transition temperature. The antiferromagnetic transition in (d) is based on literature values; white circles are from Ref. [37] and gray circles are from Ref. [38].

Figure 6

Electronic phase diagrams obtained as a function of the lattice constant at room temperature along the leg direction for the (a) $x$ dependence of ${\mathrm{BaFe}}_2{\left({\mathrm{S}}_{1-x}{\mathrm{Se}}_x\right)}_3$ and pressure dependencies of (b) $x=0$, (c) 0.25, (d) 0.60, and (e) 1. The antiferromagnetic (nematic) transitions are marked in orange (blue). The symbol types are in accordance with Fig. 1. Open gray circles are previously reported data taken from Refs. [15, 17, 20, 36]. The vertical gray dotted lines at 5.29 and 5.43 Å indicate the leg length of ${\mathrm{BaFe}}_2{\mathrm{S}}_3$ and ${\mathrm{BaFe}}_2{\mathrm{Se}}_3$. The black solid arrows correspond to the nematicity switching.