Towards building a prototype spin-logic device

<p>Since the late 1980s, several key discoveries, such as Giant and Tunneling Magne- toresistance, and advances in magnetic materials have paved the way for exponentially higher bit-densities in magnetic storage. In particular, the discovery of Spin-Transfer Torque (STT) has allowed information to be written to individual magnets using spin-currents. This has replaced the more traditional Oersted-field control used in field-MRAMs and allowed further scaling of magnetic-memories. A less obvious con- sequence of STT is that it has made possible a logic-technology based on magnets controlled by spin-polarized currents. Charge-coupled Spin Logic (CSL) is one such device proposal that couples a giant spin Hall effect(GSHE) write-unit with a Mag- netic Tunnel Junction read-unit. Several theoretical reports have demonstrated that a CSL-style device can function as a fundamental building block for neuromorphic computing by harnessing the intrinsic properties of magnets. This thesis describes the working of a CSL device. Experimental progress towards building the individual components of CSL and also our efforts to integrate these components into a CSL prototype will be presented. In addition to the integration effort, this work also explores spin-injection from a GSHE metal to a nanoscale magnet through an intermediate non-magnetic metal. Our results indicate that with the right choice of intermediate layers, the spin-angular mo- mentum absorbed by the magnet can be increased without engineering the intrinsic spin Hall angle of the GSHE metal. Finally, this work also proposes a Schottky-barrier model to describe the current flow through low-dimensional semiconductors and uses it to extract the band gap of black-phosphorus thin-films in an attempt to characterize novel 2D-materials.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Electrical and Computer Engineering

Year

2016

Author dc:creator

• Penumatcha, Ashish Verma

Contributors dc:contributor

• Joerg Appenzeller
• Zhihong Cheng
• Supriyo Datta
• Dmitri E. Nikonov

• Applied sciences
• Black phosphorus
• Giant spin Hall effect
• Schottky barriers
• Spin logic
• Spintronics
• Two dimensional materials
• Electrical and Computer Engineering
• Nanoscience and Nanotechnology

Repository record dc:identifier

https://docs.lib.purdue.edu/open_access_dissertations/986

OAI identifier oai:identifier

oai:docs.lib.purdue.edu:open_access_dissertations-2201