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While most multiferroics can't operate above room temperature, a team of researchers at Tohoku University demonstrated that terbium oxide Tb₂(MoO₄)₃ works as a multiferroic even at 160°C.

The work was published in the journal on December 18, 2024.

A material that loses its functionality on a hot summer's day, or simply due to the heat generated by the device itself, has limited practical applications. This is the major Achilles heel of multiferroics—materials that possess close coupling between magnetism and ferroelectricity. This coupling makes multiferroics an attractive area to explore, despite that weakness.

In order to surmount this weakness to unleash the full potential of multiferroics, the research team investigated the candidate material Tb₂(MoO₄)₃. It successfully showed the hallmark traits of multiferroics, and was able to manipulate electric polarization using a magnetic field, even at 160°C.

This is a huge jump from the previous limit of approximately 20°C. Without that major Achilles heel, this remarkable finding means that multiferroics can meaningfully be applied to areas such as spintronics, memory devices that consume less power, and light diodes.

"This work may pave new avenues for exploring high temperature multiferroics," says Shimon Tajima.

The researchers created this high-temperature multiferroic by combining two functionalities: the coupling between electric polarization and physical strain, known as the "piezoelectric effect," and the coupling between physical strain and magnetization, known as the "magnetoelastic effect."

This combination activated the coupling between electric polarization and magnetization, known as the "magnetoelectric effect," at high temperatures. This magnetoelectric effect is the most useful functionality of multiferroics.

"We have succeeded in raising the working temperature of multiferroics, enabling them to operate stably at room temperature or higher. This breakthrough could lead to power-saving spintronics devices, advanced optical devices, and more," adds Tajima.