Voltage controlled strain-mediated magnetization switching in ferromagnetic/ferroelectric heterostructures for low power non-volatile magnetic memory

Project Number
RP 2/16 RSR

Project Duration
November 2016 - October 2018

Status
In-Progress

Abstract
Specific Aims and Hypotheses: The main aim is to investigate voltage controlled strain mediated magnetization modulation in ferromagnetic/ferroelectric (FM/FE) heterostructures for applications in low power non-volatile memories. It is hypothesized that the power consumption in strain-mediated magnetization switching will be about two orders of magnitude lower than that of the magnetization switching driven by purely current and voltage assisted current driven magnetic memories. Methodology and Approach: Firstly, a suitable FM/FE heterostructures with large Converse Magneto-Electric (CME) coupling coefficient (a=50-100 Oe-cm/kV) will be synthesized using PLD and/or DC Magnetron Sputtering. For this, high perpendicular magnetic anisotropy (PMA) FM layer of FeCoB and/or FePt will be grown on top of FE layer of Pb[ZrxTi1-x]O3 which as large piezo-coefficient to maximize CME coupling. The voltage induced stress in FE layer will be used to alter the dimensions and hence the magneto-crystalline anisotropy of FM layer to change its magnetization direction. While PZT and FeCoB are suitable choices for FE and FM layers respectively, we will focus on investigating FePt as PMA material for FM layer as below certain thickness it is expected to sustain perpendicular anisotropy needed for FM/FE thin film heterostructure based magnetic memory. Academic Significance and Relevance to Singapore: The academic significance of project is to use superior concept of FM layer with high PMA in FM/FE heterosturcture (i) to achieve efficient strain-mediated CME coupling to facilitate non-toggle writing scheme with low power consumption and (ii) to obtain better thermal stability with no specific restriction on shape aspect ratio which further facilitates scaling to meet the present demand of high density magnetic media storage. Ultra-low power magnetization switching in ferromagnetic materials for high density magnetic memory/logic devices is highly desirable requirement of multi-billion dollar magnetic memory industry in Singapore.

Funding Source
NTU

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