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空穴掺杂Y2O3中的室温d(0)铁磁性:拓宽主体选择以定制稀磁半导体

Room temperature d (0) ferromagnetism in hole doped Y2O3: widening the choice of host to tailor DMS.

作者信息

Chakraborty Brahmananda, Ramaniah Lavanya M

机构信息

High Pressure & Synchroton Radiation Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India.

出版信息

J Phys Condens Matter. 2016 Aug 24;28(33):336001. doi: 10.1088/0953-8984/28/33/336001. Epub 2016 Jun 28.

Abstract

Transition metal-free-ferromagnetism in diluted magnetic semiconductors (DMS) is of much current interest in view of the search for more efficient DMS materials for spintronics applications. Our DFT results predict for the first time, that impurities from group1A (Li(+), Na(+), K(+)) doped on Y2O3 can induce a magnetic signature with a magnetic moment around 2.0 μ B per defect at hole concentrations around 1.63  ×  10(21) cm(-3), which is one order less than the critical hole density of ZnO with ferromagnetic coupling large enough to promote room temperature ferromagnetism. The induction of room temperature ferromagnetism by hole doping with an impurity atom from group 1A, which injects two holes per defect in the system, implies that the recommendation of three holes per defect given in the literature, which puts a restriction on the choice of host material and the impurity, is not a necessary criterion for hole induced room temperature ferromagnetism. DFT simulations with the generalized gradient approximation (GGA), confirmed by the more sophisticated hybrid functional, Heyd-Scuseria-Ernzerhof (HSE06), predict that the magnetic moment is mostly contributed by O atoms surrounding the impurity atom and the magnetic moment scale up with impurity concentration which is a positive indicator for practical applications. We quantitatively and extensively demonstrate through the analysis of the density of states and ferromagnetic coupling that the Stoner criterion is satisfied by pushing the Fermi level inside the valence band to activate room temperature ferromagnetism. The stability of the structure and the persistence of ferromagnetism at room temperature were demonstrated by ab initio MD simulations and computation of Curie temperature through the mean field approximation. This study widens the choice of host oxides to tailor DMS for spintronics applications.

摘要

鉴于寻找用于自旋电子学应用的更高效稀磁半导体(DMS)材料,无过渡金属铁磁性在当前备受关注。我们的密度泛函理论(DFT)结果首次预测,掺杂在Y2O3上的1A族杂质(Li(+)、Na(+)、K(+))在空穴浓度约为1.63×10(21) cm(-3)时,每个缺陷可诱导出约2.0 μB的磁矩,这比具有足够强铁磁耦合以促进室温铁磁性的ZnO的临界空穴密度低一个数量级。用1A族杂质原子进行空穴掺杂诱导室温铁磁性,该杂质原子在系统中每个缺陷注入两个空穴,这意味着文献中给出的每个缺陷三个空穴的建议,该建议对主体材料和杂质的选择施加了限制,并非空穴诱导室温铁磁性的必要标准。采用广义梯度近似(GGA)的DFT模拟,并经更复杂的杂化泛函Heyd-Scuseria-Ernzerhof(HSE06)证实,预测磁矩主要由杂质原子周围的O原子贡献,且磁矩随杂质浓度增加,这对实际应用是一个积极指标。我们通过对态密度和铁磁耦合的分析定量且广泛地证明,通过将费米能级推到价带内以激活室温铁磁性,满足了斯托纳准则。通过从头算分子动力学(MD)模拟和通过平均场近似计算居里温度,证明了结构的稳定性和室温下铁磁性的持续性。这项研究拓宽了主体氧化物的选择范围,可为自旋电子学应用定制DMS。

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