Magnetism of single crystalline breathing pyrochlore spinel AgInCr4S8
AgInCr4S8单晶的磁性:呼吸型pyrochlore结构
Andrew F. May, Christopher M. Pasco, V. O. Garlea, Karolina Gornicka, Matthias D. Frontzek, Xiaoping Wang, Pyeongjae Park, Andrew D. Christianson
AI总结 研究通过化学气相传输法生长AgInCr4S8单晶,并通过X射线和中子衍射验证其呼吸型pyrochlore结构,发现其在约9.6K的Neél温度以下存在长程反铁磁序,通过磁化、比热和单晶中子衍射测量揭示了其磁性特征,包括近程有序和非共轭自旋结构。
详情
- Journal ref
- Physical Review MATERIALS 10, 054410 (2026)
通过化学气相传输法生长了AgInCr4S8单晶,通过X射线和中子衍射验证了Ag/In的晶体学有序,形成了Cr$^{3+}$的呼吸型pyrochlore结构。在约9.6K的Neél温度以下观察到长程反铁磁序。通过交流和直流磁化、比热和单晶中子衍射测量表征了磁性性质。比热数据在9.5K附近显示出小的λ异常,估计的磁熵在3$T_{\mathrm N}$时达到预期值的约三分之一,表明在顺磁相中存在显著的近程有序。单晶中子衍射显示了具有传播矢量$ extbf{ extit{k}}$ = (0,0,$δ$)和$δ$ = 0.343的非共轭自旋结构,在5K时观察到。最小模型由Cr原子的铁磁层组成,磁矩位于层平面内,并在垂直方向上调制以形成沿$ extbf{ extit{k}}$传播的螺旋结构。本研究是呼吸型pyrochlore材料家族中对单晶的罕见研究。
Single crystals of \ce{AgInCr4S8} were grown by chemical vapor transport and crystallographic ordering of Ag/In that results in a breathing pyrochlore motif of Cr$^{3+}$ was verified by x-ray and neutron diffraction. Long-range antiferromagnetic order is observed below a Néel temperature of $T_{\mathrm N}$ $\approx$ 9.6 K. The magnetic properties are characterized using ac and dc magnetization, specific heat capacity, and single crystal neutron diffraction measurements. The specific heat data are characterized by a small lambda anomaly near 9.5 K and the estimated magnetic entropy reaches $\approx$ $\frac{1}{3}$ of the expected value by 3$T_{\mathrm N}$, suggesting significant short-range order in the paramagnetic phase. Single crystal neutron diffraction evidences an incommensurate spin structure with propagation vector $\textbf{\textit{k}}$ = (0,0,$δ$) and $δ$ = 0.343 at 5 K. The minimal model that accounts for the data consists of ferromagnetic layers of Cr atoms, with magnetic moments lying in the plane of the layers and modulating in the perpendicular direction to form a helical structure propagating along $\textbf{\textit{k}}$. This study represents a rare investigation of single crystals within the family of breathing pyrochlore materials.