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.
A material that loses its functionality due to heat (from the environment or 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 of research, despite that weakness.
In order to overcome this weakness, 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 major jump from the previous limit of approximately 20°C. Without that major Achilles heel, multiferroics could be applied to areas such as spintronics, memory devices that consume less power, and light diodes.
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," said the team.