DOI

https://doi.org/10.25772/W3M4-M470

Defense Date

2016

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Engineering

First Advisor

Dr. Supriyo Bandyopadhyay

Second Advisor

Dr. Jayasimha Atulasimha

Third Advisor

Dr. Puru Jena

Fourth Advisor

Dr. Gary Atkinson

Fifth Advisor

Dr. Umit Ozgur

Abstract

The ability to control the bi-stable magnetization states of shape anisotropic single domain nanomagnets has enormous potential for spawning non-volatile and energy-efficient computing and signal processing systems. One of the most energy efficient switching methods is to adopt a system of a 2-phase multiferroic nanomagnet, where a voltage applied on the piezoelectric layer generates a strain in it and the strain is elastically transferred to the magnetostrictive nanomagnet which rotates the magnetization states of the nanomagnet at room temperature via the converse magnet-electric effect. Recently, it has been demonstrated that the magnetization of a Co nanomagnet can be switched between two stable orientations by this technique. The switching probability, however, is low due to the relatively small magnetostriction of Co. One possible way to improve the statistics is to use a better magnetostrictive material like Galfenol which has much higher magnetostriction and is therefore desirable, but it also presents unique material challenges owing to the existence of many phases. Nonetheless, there is a need to step beyond elemental ferromagnets and examine compound or alloyed ferromagnets with much higher magnetostriction to advance this field. There has not been much work in nanoscale FeGa magnets which are important for nanomagnetic logic and memory applications. Here, we have experimentally demonstrated switching of magnetization of Galfenol nanomagnets and proposed a core component of ultra-energy-efficient memory cell. We also demonstrated a bit writing scheme which completely reverses the magnetization with only strain, thus overcoming the fundamental obstacle of strain induced switching of magnetizations of nanomagnets.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

6-20-2016

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