Smarter memory next-generation RAM with reduced energy consumption

Smarter memory next-generation RAM with reduced energy consumption
by Riko Seibo
Osaka, Japan (SPX) Jan 10, 2025
Efforts to enhance computing memory systems have led to the development of various advanced memory types, each aiming to address the limitations of traditional random access memory (RAM). Magnetoresistive RAM (MRAM) is among these innovations, offering non-volatility, high speed, increased storage capacity, and greater durability. Despite these advantages, reducing energy consumption during data writing remains a critical challenge for MRAM technologies.

A recent study published in Advanced Science by researchers from Osaka University introduces a novel approach to MRAM devices, significantly lowering energy usage during data writing. This new technology relies on an electric-field-based writing mechanism, offering a more energy-efficient alternative to the conventional current-based method.

Dynamic RAM (DRAM), a widely used conventional memory type, stores data in transistors and capacitors. However, this data is volatile, necessitating continuous energy input for retention. In contrast, MRAM leverages magnetic states, such as magnetization orientation, enabling non-volatile data storage without the need for constant energy input.

"As MRAM devices rely on a non-volatile magnetization state rather than a volatile charge state in capacitors, they are a promising alternative to DRAM in terms of their low power consumption in the standby state," explained Takamasa Usami, lead author of the study.

Current MRAM devices utilize electric currents to manipulate the magnetization vectors within magnetic tunnel junctions, akin to how DRAM devices manage capacitor charge states. However, the large electric currents required for this process generate significant Joule heating, increasing energy consumption.

To address this, the researchers developed a new electric-field control component for MRAM devices. Central to this innovation is a multiferroic heterostructure with magnetization vectors that can be switched using an electric field. The effectiveness of this switching is characterized by the converse magnetoelectric (CME) coupling coefficient, with higher values indicating stronger magnetization responses.

Previously, the team reported a multiferroic heterostructure with a CME coupling coefficient exceeding 10-5 s/m. However, structural inconsistencies within the ferromagnetic layer (Co2FeSi) hindered magnetic anisotropy, complicating reliable electric-field operation. To enhance stability, they introduced an ultra-thin vanadium layer between the ferromagnetic and piezoelectric layers. This addition created a clear interface, improving the magnetic anisotropy control within the Co2FeSi layer. Notably, the CME effect achieved with this configuration surpassed that of similar devices lacking the vanadium layer.

The researchers further demonstrated the ability to establish two distinct magnetic states at zero electric field by varying the electric field's sweeping operation. This capability allows for a non-volatile binary state to be reliably maintained without any applied electric field.

"Through precise control of the multiferroic heterostructures, two key requirements for implementing practical magnetoelectric (ME)-MRAM devices are satisfied: a non-volatile binary state with zero electric field and a giant CME effect," stated Kohei Hamaya, senior author.

This advancement in spintronic devices paves the way for practical applications of ME-MRAM technology. Manufacturers could utilize this low-power writing mechanism to produce efficient and reliable memory solutions suitable for various applications requiring persistent and secure data storage.

Research Report:Artificial control of giant converse magnetoelectric effect in spintronic multiferroic heterostructure