论文标题
（Mn $ _ {1-x} $ pb $ _x $）bi $ _2 $ _2 $ _4 $
Magnetic dilution effect and topological phase transitions in (Mn$_{1-x}$Pb$_x$)Bi$_2$Te$_4$
论文作者
论文摘要
作为第一个固有的抗铁磁（AFM）拓扑绝缘子（TI），MNBI $ _2 $ _2 $ _4 $提供了一个材料平台，以实现磁性和乐队拓扑相互作用引起的各种新兴现象。在这里调查（Mn $ _ {1-X} $ PB $ _X $）BI $ _2 $ _2 $ _4 $ $ $ $ $（0 \ leq x \ leq 0.82）$单晶通过X射线，电气传输，磁力测定仪，中子测量和中子测量值，化学分析，外部压力，我们的磁性效果，我们在磁性上效果MNBI $ _2 $ TE $ _4 $。随着$ x $的增加，两个晶格参数$ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a $ a。所有样品都会使用N $ \急性{e} $ el温度从$ x = 0 $ x = 0 $ x = 0.82 $的24 k降低到a $ \ acte {e} $ el温度，均以n $ \ acute {e} $ el温度降低到a型抗铁磁过渡。我们对$ x = 0.37 $样本的中子数据的完善表明，订购的力矩为4.3（1）$μ_b$/mn，在4.85 K时为4.85 K，Mn $ _ {\ rm {bi}} $ antisites的金额在误差栏中可以忽略不计。等温磁化数据显示，由于稀释磁离子并扩大了单位电池，磁层抗铁磁交换相互作用的略有减少和磁各向异性的单调减小。对于$ x = 0.37 $，外部压力的施加可增强层间抗铁磁耦合，以1.4 K/gpa的速度增强N $ \急性{E} $ EL温度，饱和场以1.8 t/gpa的速度增强。此外，我们的第一原理计算表明，两种末端材料中的频段反转分别是$γ$和$ z $点，而$ x $和$ z $ coint分别出现在$ x $和$ x = 0.44和$ x = $ x = 0.66的情况下，分别出现在$γ$和$ z $点上，分别出现在$γ$和$ z $点上，分别出现在$γ$和$ z $点上。
As the first intrinsic antiferromagnetic (AFM) topological insulator (TI), MnBi$_2$Te$_4$ has provided a material platform to realize various emergent phenomena arising from the interplay of magnetism and band topology. Here by investigating (Mn$_{1-x}$Pb$_x$)Bi$_2$Te$_4$ $(0\leq x \leq 0.82)$ single crystals via the x-ray, electrical transport, magnetometry and neutron measurements, chemical analysis, external pressure, and first-principles calculations, we reveal the magnetic dilution effect on the magnetism and band topology in MnBi$_2$Te$_4$. With increasing $x$, both lattice parameters $a$ and $c$ expand linearly by around 2\%. All samples undergo the paramagnetic to A-type antiferromagnetic transition with the N$\acute{e}$el temperature decreasing lineally from 24 K at $x=0$ to 2 K at $x=0.82$. Our neutron data refinement of the $x=0.37$ sample indicates that the ordered moment is 4.3(1)$μ_B$/Mn at 4.85 K and the amount of the Mn$_{\rm{Bi}}$ antisites is negligible within the error bars. Isothermal magnetization data reveal a slight decrease of the interlayer plane-plane antiferromagnetic exchange interaction and a monotonic decrease of the magnetic anisotropy, due to diluting magnetic ions and enlarging the unit cell. For $x=0.37$, the application of external pressures enhances the interlayer antiferromagnetic coupling, boosting the N$\acute{e}$el temperature at a rate of 1.4 K/GPa and the saturation field at a rate of 1.8 T/GPa. Furthermore, our first-principles calculations reveal that the band inversion in the two end materials, MnBi$_2$Te$_4$ and PbBi$_2$Te$_4$, occurs at the $Γ$ and $Z$ point, respectively, while two gapless points appear at $x = $ 0.44 and $x = $ 0.66, suggesting possible topological phase transitions with doping.
