Tailoring magnetic properties of Mn-Cr chalcogenide alloys and heterostructures

调整 Mn-Cr 硫系合金和异质结构的磁性能

• 批准号: EP/M022188/1
• 负责人: Daniel Wolverson
• 金额: $ 55.08万
• 依托单位: University of Bath
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2015
• 资助国家: 英国
• 起止时间: 2015 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FM022188%2F1
• 关键词: Tailoring; magnetic; properties; Mn; Cr

We shall develop new, thin-layer materials composed of transition metal elements (Cr, Mn) combined with group VI elements (S, Se,Te); these little-known materials offer the prospect of satisfying the requirements for a wide range of spin-dependent electronic ("spintronic") devices. This proposal aims to take the first steps in making and investigating single- and multi-layer materials from this family with the necessary compositions and crystal quality, but we shall also manufacture and study selected demonstrator devices within the timescale of the project. The term "spintronics" encompasses many proposed devices (for example, but not exclusively, sensors, memory elements, diodes and transistors) in which it is the spin of the electrons that is manipulated in order to sense, store, carry or process information. In other words, these devices exploit the intrinsic magnetic properties of electrons as well as their charge and, as a result, may offer improvements in energy efficiency, speed or size. The prizes for the realization of such devices are enormous; for example, the phenomenal commercial success of the device at the heart of hard disk read heads (which can be classed as a spintronic device) has stimulated great excitement and intense research efforts aiming at wider applications of spin. Despite this, it has not proved possible to produce industrially-useful magnetic semiconductors from the first few candidate materials identified by early theoretical predictions. As a result, many groups in the worldwide spintronics community are now engaged in widening both the scope of the materials considered, and the types of magnetic behaviour that can be exploited; this search has revitalised the whole field of spintronics. This proposal addresses a candidate material family that has been proposed in the theoretical literature but (apart from our trials) has not yet been produced in the laboratory. The (Cr, Mn)(S,Se,Te) material family satisfies several crucial requirements. Firstly, thin layers of these compounds will be grown on industry standard GaAs substrates and will adopt the same crystal structure as the substrate. This makes the resulting structures highly compatible with existing semiconductor technologies. Secondly, preliminary studies of ours and theoretical studies of several groups imply that we will be able to produce all the potentially useful types of magnetic behaviour by tuning the composition. These include ferromagnets and half-metals (where the transition metal magnetic moments align parallel to each other and add), antiferromagnets (where they align oppositely and cancel) and ferrimagnets (where dissimilar transition metals align oppositely but are not equivalent and so cannot exactly cancel). Layers of any of the above magnetic types can form the active layer in different types of spintronic devices. Thirdly, these materials are chemically and structurally compatible with non-magnetic semiconductors (e.g, ZnSe, MgS) that we can grow as parts of multi-layer structures; these allow the necessary electrical contacts and electrical barriers to be formed. Our programme will involve a substantial effort in growing these new materials to obtain layers of high crystal quality; preliminary work indicates that there will be no fundamental obstacles to success. The structural, magnetic and electrical properties of the materials will be investigated to identify the most promising compositions and most appropriate target device designs based on them. Demonstrator devices will then be produced to test how the materials perform in realistic device contexts and to promote interest in the work. This work requires a broad base of experience and so we have formed a team having expertise in MBE growth, electrical device fabrication and measurement, magneto-optical spectroscopy and magnetometry.

我们将开发由过渡金属元件（CR，MN）组成的新型薄层材料，结合了VI组元素（S，SE，TE）；这些鲜为人知的材料提供了满足对各种自旋依赖性电子（“旋转”）设备的要求的前景。该提案旨在采取第一步，从该家族制造和调查具有必要组成和晶体质量的单层和多层材料，但我们还将在该项目的时间范围内生产和研究选定的演示器设备。术语“旋转器”涵盖了许多提出的设备（例如，但不是仅限于传感器，内存元素，二极管和晶体管），其中是对电子的旋转操作以感知，存储，携带或处理信息的旋转。换句话说，这些设备利用电子的固有磁性特性以及它们的电荷，因此可以提高能效，速度或尺寸。实现此类设备的奖品是巨大的；例如，该设备在硬盘读取头的核心（可以归类为旋转器设备的核心）的惊人商业成功刺激了极大的兴奋和激烈的研究工作，目的是旨在更广泛的旋转应用。尽管如此，尚未证明可以从早期理论预测确定的前几种候选材料中产生具有工业用途的磁性半导体。结果，世界范围内的旋转统治社区中的许多群体现在都在扩大所考虑的材料范围和可以利用的磁性行为的类型。这次搜索使整个Spintronics的领域振兴了。该提议涉及一个候选物质家族，该家族已在理论文献中提出，但（除了我们的试验之外）尚未在实验室中生产。 （CR，MN）（S，SE，TE）材料家族满足了一些至关重要的要求。首先，这些化合物的薄层将在行业标准GAAS基板上生长，并将采用与底物相同的晶体结构。这使得最终的结构与现有的半导体技术高度兼容。其次，对我们的初步研究和几个小组的理论研究表明，我们将能够通过调整组成来产生所有潜在的磁性行为类型。其中包括铁磁体和半米（过渡金属磁矩彼此平行并添加），抗铁磁铁（它们对齐并取消）和ferrimagnets（在其中不同的过渡金属对齐相反，但不能完全相等，因此不能完全取消取消）。上述任何一种磁性类型的层都可以在不同类型的自旋设备中形成活性层。第三，这些材料在化学和结构上与非磁性半导体（例如ZNSE，MGS）兼容，我们可以作为多层结构的一部分生长。这些允许形成必要的电触点和电屏障。我们的计划将涉及种植这些新材料以获得高晶体质量的巨大努力。初步工作表明，没有成功的根本障碍。将研究材料的结构，磁性和电气性能，以确定基于它们的最有希望的组成和最合适的目标装置设计。然后，将生产演示器设备，以测试材料在现实设备上下文中的性能并促进对工作的兴趣。这项工作需要广泛的经验基础，因此我们组成了一个在MBE增长，电气装置制造和测量，磁光谱和磁力测定方面具有专业知识的团队。

项目成果

Identifying light impurities in transition metal dichalcogenides: the local vibrational modes of S and O in ReSe2 and MoSe2

• DOI: 10.1038/s41699-017-0043-1
• 发表时间: 2017-11
• 期刊: npj 2D Materials and Applications
• 影响因子: 9.7
• 作者: L. Hart;J. Webb;Stephen Murkin;D. Wolverson;D. Lin

Strain-induced phonon shifts in tungsten disulfide nanoplatelets and nanotubes

• DOI: 10.1088/2053-1583/4/1/015007
• 发表时间: 2017-03-01
• 期刊: 2D MATERIALS
• 影响因子: 5.5
• 作者: Wang, Fang;Kinloch, Ian A.;Young, Robert J.
• 通讯作者: Young, Robert J.

Lattice Dynamics of the Rhenium and Technetium Dichalcogenides.

• DOI: 10.1186/s11671-016-1459-9
• 发表时间: 2016-12
• 期刊: Nanoscale research letters
• 作者: Wolverson D;Hart LS
• 通讯作者: Hart LS