Heat induced phase change exchange coupled composite media (HIP-ECC)

今天，数据存储市场由磁性硬盘驱动器（HDD）主导，这是由于与竞争对手技术（例如，硬盘驱动器）相比，它们具有成本效益和实用性。固态闪存驱动器）。自50多年前发明以来，HDD的基本布局一直保持不变，但组件的技术已经发生了超乎想象的变化，这导致自第一个硬盘驱动器以来数据存储容量增加了2亿倍。如果没有科学进步和工程能力携手合作所取得的这一非凡成就，今天的信息社会就不可能实现。例如，在HDD数据读取器中使用的巨磁电阻（GMR）效应的发现在2007年被授予诺贝尔物理学奖。该项目旨在探索磁盘介质的新想法，以使未来社会进步所需的数据存储容量继续显着增长。HDD的成功建立在科学和技术进步的基础上，使每个组件都可以扩展到不断缩小的尺寸。传统磁记录介质中使用的材料是纳米级（~ 8 nm）颗粒磁体，其中使用电磁体将单个比特存储在多个颗粒上，该电磁体被设计为在磁盘表面上方几纳米处飞行。这些晶粒不能无限地按比例缩小尺寸，并且由于晶粒的体积受到超顺磁效应的限制，其中单个磁性晶粒可能由于热激发而反转，导致数据丢失和器件故障。在曼彻斯特大学和谢菲尔德大学的联合项目中，我们提出了一种用于热辅助磁记录（HAMR）的可调谐交换耦合复合（ECC）介质的新设计：热致相变ECC介质（HIP-ECC）。交换耦合复合介质通常由紧密接触的几个纳米厚的硬磁和软磁材料层组成。通过与软层耦合来辅助硬层的磁切换，从而基于硬层的性质产生较低的总体切换场和较高的热稳定性。所提出的可调谐ECC介质在软层和硬层之间具有中间层，其将允许使用温度变化来控制两个层之间的交换能量/耦合。这种热开关将使我们能够大大减少记录的热量需求，从而避免了HAMR更传统方法的许多困难。这种设计的主要优点是可以使用一种热稳定性极高的材料来存储数据，而不会损失可写性。HAMR是实现磁记录中更高数据存储密度的领先技术候选者。该技术的优点在于，它可以与现有的和未来的数据记录技术一起使用，即传统的磁性介质和比特图案化介质（磁性材料被图案化成单独的纳米级岛，每个岛记录单个比特的数据）。HAMR利用在高温下切换铁磁体所需的磁场的减少。这种现象允许使用最高的磁晶各向异性材料，如高度有序的FePt和CoPt合金，以保持长期稳定性。磁晶各向异性是材料的内部属性，决定了其磁热稳定性。通过该项目，我们的目标是提供科学进步，从而在磁数据存储中实现明确的应用，使下一代HDD产品得以生产。使用这种技术，数据存储密度理论上可以增加到20 Tbit/in 2，比目前的商业磁盘驱动器大40倍。

Today the data storage market is dominated by magnetic hard disk drives (HDDs) due to their cost effectiveness and utility compared with competitor technologies (eg. solid state flash drives). The basic layout of a HDD has remained the same since they were invented more than 50 years ago, but the technology of the components has changed beyond imagination and this has led to a 200 million-fold increase in data storage capacity since the first hard disk drives. Today's information society would not be possible without this extraordinary accomplishment which has occurred as a result of scientific advancement and engineering prowess working hand in hand. As an example, the discovery of the giant magnetoresistance (GMR) effect used in HDD data readers for which the Nobel Prize in Physics was awarded in 2007. This project aims to explore new ideas for magnetic disk media to allow a continuation of the phenomenal growth in data storage capacities that is required for societal progress in the future.The success of HDDs has been built on the scientific and technological progress that has allowed each of the components to be scaled to ever decreasing size. The materials used in conventional magnetic recording media are nanoscale (~8nm) granular magnets where a single bit is stored on multiple grains using an electromagnet designed to fly a few nanometres above the surface of the disk. These grains cannot be scaled down in size indefinitely and as the volume of the grain is limited by the super-paramagnetic effect, where individual magnetic grains may reverse due to thermal excitations, results in data loss and device failure. Recent research has focussed on circumventing this problem.In this joint project between the University of Manchester and the University of Sheffield we propose a new design for a tuneable exchange coupled composite (ECC) medium for heat assisted magnetic recording (HAMR); a heat induced phase change ECC medium (HIP-ECC). An exchange coupled composite medium typically consists of several nanometre thick layers of magnetically hard and soft materials in intimate contact. Magnetic switching of the hard layer is assisted by coupling with the soft layer, resulting in a lower overall switching field and a higher thermal stability based on the properties of the hard layer. The proposed tuneable ECC medium has an intermediate layer between the soft and hard layer that will allow control of the exchange energy/coupling between both layers using a change in temperature. This thermal switch will allows us to dramatically reduce the heat requirements for recording, thereby avoiding many of the difficulties of more conventional approaches to HAMR. The key advantage of this design is that an extremely thermally stable material can be used to store the data with no loss in writeability.HAMR is the leading technological candidate for achieving higher data storage densities in magnetic recording. This technology has the advantage that it can be used with both existing and future data recording technologies i.e. conventional magnetic media and bit patterned media (the magnetic material is patterned into individual nanometre-scale islands, each recording a single bit of data). HAMR makes use of the reduction in the magnetic field required to switch a ferromagnet at elevated temperatures. This phenomenon allows the use of the highest magneto-crystalline anisotropy materials such as highly ordered FePt and CoPt alloys to maintain long term stability. Magneto-crystalline anisotropy is an internal property of the material that determines its magnetic thermal stability.Through this project we aim to deliver scientific progress that will result in clear applications in magnetic data storage, enabling the next generation of HDD products to be produced. Using this technology data storage density can theoretically be increased to 20Tbit/in2, 40 times larger than current commercial disk drives.