Interface induced magnetic properties of thin films

近三十年来，由于铁磁材料中界面感应现象的发现，使得磁存储器存储密度的快速增长成为可能|非磁性（NM）多层膜。巨磁阻和隧道磁阻现象的发现使得能够检测磁矩方向，并且是磁传感器设计的关键，这些传感器负责将硬盘驱动器的记录密度增加>100倍。自旋转移力矩（STT）和自旋轨道力矩的观测（用于操纵磁矩方向）允许固态非易失性磁性存储器的新颖设计，其被识别为存储器装置中的下一代。 另一个被深入研究的界面效应是层间交换耦合。直到现在，这种现象还没有被充分利用，因为传统的耦合层只允许FM层的磁矩的共线取向。最近，我们发现并申请了新的耦合层（CL）材料，其可以代替NM插入到两个铁磁层之间，以精确地控制FM中FM层的磁矩的相对取向。|CL|温州组这些新的耦合层具有用于大多数磁性纳米器件的潜力，因为磁性纳米器件的最佳设计几乎总是需要至少两个相邻铁磁层之间的非共线对准。 这个建议的重点是了解FM中非共线耦合的起源|CL| FM结构以及如何将这些结构纳入磁性纳米器件。重点将放在设备上，这些设备可以从磁矩的非共线排列，自旋转移矩磁性随机存取存储器（STT MRAM）和纳米振荡器中受益最多。具有磁矩的非共线对准的STT MRAM预期具有比当前最先进的STT MRAM装置快得多的写入速度和显著低的功率消耗。加拿大将受益于已经和将要产生的重要知识产权，这可能为HQP在加拿大开发这些纳米器件创造机会。除了研究静态效应，如层间耦合，我们还将研究磁化动态效应，在FM自旋泵|NM接口，和随后的运输纯自旋电流NM。特别感兴趣的是NM = Pt和Pd，因为它们在与铁磁膜界面连接时表现出邻近磁化。Pt和Pd还强烈地影响铁磁层的磁静态和动态性质，这可能是有益的，如表面各向异性的增加，或有害的，如磁阻尼的增加。我们将利用自旋泵浦和逆自旋霍尔效应来研究与Pt和Pd相邻的铁磁层的阻尼增加的机制。

The rapid increase in magnetic memory storage density over the last three decades has been made possible by the discovery of interface-induced phenomena in ferromagnetic (FM)|non-magnetic (NM) multilayers. The discovery of giant magnetoresistance and tunnel magnetoresistance phenomena enabled the detection of magnetic moment direction and are key for the design of magnetic sensors that are responsible for >100 times increase in the recording density of hard drives. The observation of spin transfer torque (STT) and spin orbit torque, utilized to manipulate the magnetic moment direction, allows for a novel design of solid state non-volatile magnetic memories, which are identified as the next generation in memory devices. Another interface effect that has been intensively studied is the interlayer exchange coupling. This phenomenon has not been used to its full potential until now, since traditional coupling layers only allow for collinear orientation of magnetic moments of FM layers. Recently, we discovered and patented new coupling layer (CL) materials, which can be inserted instead of NM, between two ferromagnetic layers to precisely control the relative orientation of the magnetic moments of FM layers in FM|CL|FM. These new coupling layers have the potential to be used in the majority of magnetic nanodevices since the optimal design of magnetic nanodevices almost always requires non-collinear alignment between at least two neighboring ferromagnetic layers. This proposal focuses on understanding the origin of non-collinear coupling in FM|CL|FM structures and how to incorporate these structures into magnetic nanodevices. The emphasis will be on devices, which could benefit most from non-collinear alignment of magnetic moments, spin transfer torque magnetic random-access memories (STT MRAM), and nano-oscillators. STT MRAM with non-collinear alignment of magnetic moments are expected to have much faster write speeds and significantly low power consumption than the current state-of-the-art STT MRAM devices. Canada will benefit from significant intellectual property that has already been and will be generated, which could create an opportunity for HQP to develop these nanodevices in Canada. In addition to studying static effects, such as interlayer coupling, we will also study magnetization dynamic effects, spin pumping at FM|NM interfaces, and the subsequent transport of pure spin current in NM. Of specific interest are NM = Pt and Pd since they exhibit proximity magnetization when interfaced with ferromagnetic films. Pt and Pd also strongly affect magnetic static and dynamic properties of ferromagnetic layers, which can be beneficial like increase of surface anisotropy or detrimental like increase of magnetic damping. We will study the mechanisms responsible for increase of damping of ferromagnetic layers adjacent to Pt and Pd by means of spin pumping and inverse spin Hall effect.