Current-driven domain wall motion and magnetomemristance in FeRh-based nanostructures

FeRh 基纳米结构中电流驱动的畴壁运动和磁阻

基本信息

批准号：
EP/M018504/1
负责人：
Christopher Marrows
金额：
$ 87.42万
依托单位：
University of Leeds
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%2FM018504%2F1
关键词：
Current driven domain wall motion

项目摘要

This project will study current-driven motion of antiferromagnetic/ferromagnetic (AF/FM) domain walls (DWs) in FeRh-based nanostructures. This will both elucidate the fundamental physics of the phase transition and also explore the potential for (magneto-)memristor devices, based on our prior demonstration of temperature/field controlled DW motion in an FeRh epilayer with a doping gradient. Memristors are devices suitable for ultradense non-volatile memory and also show many of the characteristics of an artificial synapse, opening the door to novel neuromorphic memory and logic architectures that promise enhanced functionality and low energy operation in future generations of ITC hardware. To achieve this goal we first need to know what doping materials and densities are required to control the AF-FM phase transition temperature, provide appropriate hysteresis in the transition (to store information), and largest possible resistivity change (for readout) between the AF and FM phases, as well as what parameters (materials and densities) would describe an ideal doping gradient. Next, we will need to establish how small a magnetic nanostructure can be formed from FeRh and retain a suitable AF/FM transition, and the precise conditions and requirements that permit the smallest nanostructures to be stable. Then it will be necessary to establish the current densities needed to move the domain walls that separate ferromagnetic and antiferromagnetic regions in the phase-separated regime of FeRh. Last, we will need to demonstrate a memristive action under current-driven domain wall motion in a nanostructure with a suitable doping gradient.Our project will combine state-of-the-art magnetic materials growth, characterisation, direct imaging of these novel DWs, and device fabrication and test, taking us from basic materials development to a fully operational magneto-memristor prototype nanostructure. We will begin by sputter-depositing uniformly- and gradient-doped FeRh epilayer materials and measuring their magnetic and magnetotransport properties, which will tell us the dopant materials and doping levels needed to achieve optimal memristive action. We will then fabricate nanostructures down to the few 10s of nm scale from the optimally doped FeRh layers, either as individual nanostructures (for microscopy) or as large-scale arrays of nanostructures (for magnetometry), which will reveal the minimum size at which a phase transition that is useful for memristive action is retained. Next, we will carry out world-first experiments on current-driven AF/FM domain wall motion in lateral FeRh nanowires, using magnetic microscopy to track the motion of DWs in response to current pulses, revealing the efficiency of spin injection for DW motion and the degree and nature of DW pinning arising from different sources. We will then pattern nanopillars from gradient-doped layers and study DW motion driven by a vertical current in a prototype memristor device, using both magnetotransport measurements and direct imaging of the internal structure of the device. The key result will be the magneto-memristance as a function of device size, temperature, and magnetic field. The results we shall obtain will not only lead to high impact publications and conference presentations by shedding light on the still poorly understood fundamental problem of the nature of the phase transition in FeRh, but also reveal the performance characteristics of the world's first magneto-memristor, developing potentially valuable knowhow in the field of novel neuromorphic computer architectures.

该项目将研究基于FERH的纳米结构中抗铁磁/铁磁（AF/FM）域壁（DWS）的电流运动。这既可以阐明相变的基本物理，又基于我们先前在用掺杂梯度的FERH EPOLAYEER中对温度/场控制DW运动进行的证明，探索了（磁性）Memristor设备的潜力。回忆录是适用于超高非易失性记忆的设备，还显示了人工突触的许多特征，为新颖的神经形态记忆和逻辑体系结构打开了大门，在未来几代ITC硬件中有望增强功能和低能运行。为了实现这一目标，我们首先需要知道需要哪些掺杂材料和密度来控制AF-FM相过渡温度，在过渡中提供适当的滞后（用于存储信息），以及在AF和FM相之间的最大电阻率变化（用于读取），以及哪些参数（材料和密度）将描述理想的掺杂梯度。接下来，我们将需要确定如何从FERH形成磁性纳米结构并保留合适的AF/FM过渡，以及允许最小纳米结构稳定的确切条件和要求。然后，有必要建立移动域壁所需的当前密度，这些域壁将FERH相分离状态中分离铁磁和抗铁磁区域。最后，我们将需要在纳米结构中表现出在纳米结构中具有适当掺杂梯度的纳米结构壁运动下的回忆作用。您的项目将结合最先进的磁性材料的增长，表征，对这些新颖的DWS的直接成像以及设备制造和测试，从基本材料开发中，从基本材料开发到完全操作的Magneto-Memmristor prototypore prototypepe型Nananosstruct。我们将首先溅射沉积均匀和梯度的Ferh Epolayer材料，并测量其磁性和磁转运性能，这将告诉我们实现最佳磁性作用所需的掺杂材料和掺杂水平。然后，我们将从最佳掺杂的FERH层（用于显微镜）或大规模纳米结构（用于磁力测定法）的大型纳米结构（用于显微镜）中，将纳米结构从最佳掺杂的FERH层制造至NM比例的几个10s，这将揭示对最小尺寸的最小尺寸，该尺寸可用于磁性作用有用。接下来，我们将使用磁显微镜在侧向FERH纳米线中对电流驱动的AF/FM域壁运动进行世界优先实验，从而跟踪DWS对电流脉冲的响应，从而揭示了DW运动的旋转效率以及DW运动的效率以及DW固定的程度和性质来自不同来源。然后，我们将使用Magnetotransport测量和对设备内部结构的直接成像进行原型Memristor设备中的垂直电流驱动的DW运动，从而研究由垂直电流驱动的DW运动。关键结果将是磁磁体随着设备尺寸，温度和磁场的函数的函数。我们将获得的结果不仅会导致高影响出版物和会议演讲，从而阐明了FERH中相过渡性质的基本问题仍然不足，而且还揭示了世界上第一个磁磁性磁盘的性能特征，并在新型神经型计算机建筑领域发展了潜在的有价值的知识。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Direct visualization of the magnetostructural phase transition in nano-scale FeRh thin films using differential phase contrast imaging

使用微分相差成像直接可视化纳米级 FeRh 薄膜中的磁结构相变

DOI：
10.48550/arxiv.1909.03966
发表时间：
2019
期刊：
影响因子：
0
作者：
Almeida T
通讯作者：
Almeida T

Magnetothermodynamic Properties and Anomalous Magnetic Phase Transition in FeRh Nanowires

FeRh 纳米线的磁热力学性质和反常磁相变

DOI：
10.1109/tmag.2018.2832191
发表时间：
2018
期刊：
IEEE Transactions on Magnetics
影响因子：
2.1
作者：
Matsumoto K
通讯作者：
Matsumoto K

Quantitative TEM imaging of the magnetostructural and phase transitions in FeRh thin film systems.

DOI：
10.1038/s41598-017-18194-0
发表时间：
2017-12-19
期刊：
Scientific reports
影响因子：
4.6
作者：
Almeida TP;Temple R;Massey J;Fallon K;McGrouther D;Moore T;Marrows CH;McVitie S
通讯作者：
McVitie S

Direct visualization of the magnetostructural phase transition in nanoscale FeRh thin films using differential phase contrast imaging