Performing ab initio calculations, we investigate electronic and magnetic properties of a silicon allotrope (PH-silicene) composed entirely by six silicon pentagons and two silicon hexagons. The dynamically and mechanically stable PH-silicene hosts two-dimensional honeycomb spin structures, which can be antiferromagnetic, ferromagnetic, or ferrimagnetic depending on the applied tensile strain and/or number of stacked layers. In particular, the transition temperature of an in-plane antiferromagnetic ground state and a strain-induced ferromagnetic state of monolayer PH-silicene is found to be around 533 and 80 K, respectively. This unusual metal-free magnetism can be explained by the d0 charge transfer mechanism. On the other hand, we show that the PH-silicene is an indirect semiconductor with the bandgap of 0.585 eV. When stacking up to 4-layers, they vary from the semiconductor, the semimetal to the normal metal. Our findings suggest PH-silicene as a promising candidate for the room temperature magnetic semiconductor and will pave a way for silicon based spintronic devices.

中文翻译：

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五六硅烯：本征室温磁性半导体的有前途的候选者

通过从头计算，我们研究了完全由六个硅五边形和两个硅六边形组成的硅同素异形体（PH-硅烯）的电子和磁性。动态和机械稳定的 PH-硅质拥有二维蜂窝自旋结构，根据施加的拉伸应变和/或堆叠层数，它可以是反铁磁、铁磁或亚铁磁。特别是，发现单层 PH-硅烯的面内反铁磁基态和应变诱导铁磁态的转变温度分别约为 533 和 80 K。这种不寻常的无金属磁性可以用 d0 电荷转移机制来解释。另一方面，我们表明 PH-硅烯是一种带隙为 0.585 eV 的间接半导体。最多堆叠 4 层时，它们从半导体、半金属到普通金属各不相同。我们的研究结果表明 PH-硅烯是室温磁性半导体的有前途的候选者，并将为硅基自旋电子器件铺平道路。