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首页> 外文学位 >Nonvolatile spin memory based on diluted magnetic semiconductor and hybrid semiconductor ferromagnetic nanostructures.
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Nonvolatile spin memory based on diluted magnetic semiconductor and hybrid semiconductor ferromagnetic nanostructures.

机译：基于稀释的磁性半导体和混合半导体铁磁纳米结构的非易失性自旋存储器。

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摘要

The feasibility of two nonvolatile spin-based memory device concepts is explored. The first memory device concept utilizes the electrically controlled paramagnetic-ferromagnetic transition in a diluted magnetic semiconductor layer (quantum well or dot) when the ferromagnetism in the diluted magnetic semiconductor is mediated by itinerant holes. The specific structure under consideration consists of a diluted magnetic semiconductor quantum well (or quantum dot) that exchanges holes with a nonmagnetic quantum well, which acts as a hole reservoir. The quantitative analysis is done by calculating the free energy of the system. It takes into account the energy of holes confined in a nanostructure and the magnetic energy. Formation of two stable states at the same external conditions, i.e., bistability, is found feasible at temperatures below the Curie temperature with proper band engineering. The effect of scaling the magnetic quantum well to a quantum dot on bistability is analyzed. The bit retention time, i.e., lifetime, with respect to spontaneous leaps between the two stable states is calculated. The write/erase and read operations as well as the dissipation energy are discussed. Also, potential logic operations are proposed. In the second memory concept, the active region is a semiconductor quantum dot sharing an interface with a dielectric magnetic layer. The operating principle of the device is based on the spontaneous magnetic symmetry breaking due to exchange interaction between the magnetic ions in the magnetic layer and spins of the confined holes in the quantum dot. The quantitative analysis considers the holes thermal distribution over the energy spectrum in the quantum dot, hole-hole interaction, exchange interaction between the holes and the magnetic ions, and magnetic energy of the magnetic insulator. Room temperature operation is possible given the availability of insulating ferromagnetic or antiferromagnetic materials whose Curie or Neel temperature is above room temperature. The specific range of material parameters where bistability is achieved is found. Analysis is extended to different quantum dot and magnetic dielectric materials and designs. The influence of material choice and design on the memory robustness and lifetime is discussed.
机译：探索了两种基于自旋的非易失性存储设备概念的可行性。当稀磁半导体中的铁磁性由流动空穴介导时，第一种存储设备的概念利用稀磁半导体层（量子阱或点）中的电控顺磁-铁磁跃迁。所考虑的特定结构由稀释的磁性半导体量子阱（或量子点）组成，该量子阱与充当空穴存储区的非磁性量子阱交换空穴。通过计算系统的自由能来完成定量分析。它考虑了限制在纳米结构中的空穴的能量和磁能。已经发现，在低于居里温度的温度下，通过适当的能带工程，在相同的外部条件下形成两个稳定状态，即双稳性是可行的。分析了将磁性量子阱按比例缩放成量子点对双稳态的影响。计算相对于两个稳定状态之间的自发跳跃的位保留时间，即寿命。讨论了写入/擦除和读取操作以及耗散能量。此外，提出了潜在的逻辑运算。在第二存储概念中，有源区是与介电磁性层共享界面的半导体量子点。该装置的工作原理基于由于磁性层中的磁性离子与量子点中的受限空穴的自旋之间的交换相互作用而导致的自发磁性对称性破坏。定量分析考虑了空穴在量子点的能谱上的热分布，空穴与空穴的相互作用，空穴与磁离子之间的交换相互作用以及磁绝缘体的磁能。考虑到居里或尼尔温度高于室温的绝缘铁磁或反铁磁材料的可用性，可以在室温下运行。找到实现双稳性的材料参数的特定范围。分析扩展到了不同的量子点和磁电介质材料和设计。讨论了材料选择和设计对存储器健壮性和寿命的影响。

著录项

  • 作者

    Enaya, Hani A.;

  • 作者单位

    North Carolina State University.;

  • 授予单位 North Carolina State University.;
  • 学科 Electrical engineering.
  • 学位 Ph.D.
  • 年度 2008
  • 页码 125 p.
  • 总页数 125
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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