论文标题
反铁磁性TBFE $ _ {0.5} $ CR $ _ {0.5} $ o $ $ $ _3 $中的重入旋转重新定向转变和类似Griffiths的阶段
Reentrant spin reorientation transition and Griffiths-like phase in antiferromagnetic TbFe$_{0.5}$Cr$_{0.5}$O$_3$
论文作者
论文摘要
The perovskite TbFe$_{0.5}$Cr$_{0.5}$O$_3$ shows two anomalies in the magnetic susceptibility at $T_N$ = 257K and $T_{SR}$ = 190K which are respectively, the antiferromagnetic and spin reorientation transition that occur in the Fe/Cr sublattice.对磁敏感性的分析揭示了该化合物中类似Griffiths的标志。中子衍射分析证实，随着温度从350K降低，旋转重新定位从$γ_2$（f $ _x $，c $ _y $，g $ _z $）到$γ_4$（g $ _x $，$ _y $，f $ _z $）在$ _ $，f $ _z $中均以$ t_n $ = 257的速度出现。 $γ_4$（g $ _x $，a $ _y $，f $ _z $）至$γ_2$（f $ _x $，c $ _y $，g $ _z $），$ t_ {sr} $ = 190k。 $γ_2$（f $ _x $，c $ _y $，g $ _z $）结构一直稳定，直到7.7k为7.74（1）$μ__\ MATHRM B $/Fe $^{3+} $（CR $^{3+} $）的订购矩，从中子数据进行了细化。除了磁性结构的远距离顺序外，在7.7K处的弥散磁散射的指示很明显，从而在易感性中观察到的类似Griffiths的相位支持。在7.7K时，结核病沿晶体学$ a $轴开发了铁磁成分。在本工作中研究了TBFE $ _ {0.5} $ CR $ _ {0.5} $ CR $ _ {0.5} $ cr $ _3 $的导热率和旋转偶联。具有（$ \ uparrow \ downrow \ uparrow \ downarrow $）Fe/cr旋转的反铁磁性结构，通过在基态下通过第一原理能量计算找到，该计算支持7.7K的实验磁性结构。确定旋转分辨的状态总密度和部分密度，表明tbfe $ _ {0.5} $ cr $ _ {0.5} $ o $ _3 $在GGA（GGA+$ U $）功能中的频段间隙为$ \ sim 0.12 $（2.4）ev的频段间隙。
The perovskite TbFe$_{0.5}$Cr$_{0.5}$O$_3$ shows two anomalies in the magnetic susceptibility at $T_N$ = 257K and $T_{SR}$ = 190K which are respectively, the antiferromagnetic and spin reorientation transition that occur in the Fe/Cr sublattice. Analysis of the magnetic susceptibility reveals signatures of Griffiths-like phase in this compound. Neutron diffraction analysis confirms that, as the temperature is reduced from 350K, a spin reorientation transition from $Γ_2$ (F$_x$, C$_y$, G$_z$) to $Γ_4$ (G$_x$, A$_y$, F$_z$) occurs at $T_N$ = 257K and subsequently, a second spin reorientation takes place from $Γ_4$ (G$_x$, A$_y$, F$_z$) to $Γ_2$ (F$_x$, C$_y$, G$_z$) at $T_{SR}$ = 190K. The $Γ_2$ (F$_x$, C$_y$, G$_z$) structure is stable until 7.7K where an ordered moment of 7.74(1)$μ_\mathrm B$/Fe$^{3+}$(Cr$^{3+}$) is obtained from neutron data refinement. In addition to the long-range order of the magnetic structure, indication of diffuse magnetic scattering at 7.7K is evident, thereby lending support to the Griffiths-like phase observed in susceptibility. At 7.7K, Tb develops a ferromagnetic component along the crystallographic $a$ axis. Thermal conductivity, and spin-phonon coupling of TbFe$_{0.5}$Cr$_{0.5}$O$_3$ through Raman spectroscopy are studied in the present work. An antiferromagnetic structure with ($\uparrow \downarrow \uparrow \downarrow$) arrangement of Fe/Cr spins is found in the ground state through first-principles energy calculations which supports the experimental magnetic structure at 7.7K. The spin-resolved total and partial density of states are determined showing that TbFe$_{0.5}$Cr$_{0.5}$O$_3$ is insulating with a band gap of $\sim 0.12$ (2.4) eV within GGA (GGA+$U$) functionals.
