An international research team led by Osaka Metropolitan University has created a material that can control, direct, and remember heat like a microchip stores data — breaking one of the most fundamental rules of thermodynamics in the process.
Normally, a material absorbs and emits heat in a linked, symmetrical way: a surface that absorbs heat efficiently at a certain wavelength and direction will also emit heat in exactly the same way. This principle, known as thermal reciprocity, has long limited our ability to independently control heat absorption and emission.
The new device shatters that constraint.
How It Works
The team combined two advanced technologies: - Magneto-optical materials, whose interaction with light can be altered using a magnetic field - GST, a specialized phase-change material that acts as both a switch and a memory cell
Built into nanoscale architectures called metagratings, the device can absorb heat from one direction and emit it in another — even at near-normal angles of incidence, a dramatic improvement over previous attempts that required extreme angles where efficiency collapsed.
Crucially, the device remembers its thermal state even after power is disconnected, just like non-volatile computer memory.
"We made heat radiation behave in a 'smarter' way," said Dr. Shunsuke Murai from Osaka Metropolitan University's Graduate School of Engineering. "Achieving these capabilities in a working model could enable a new generation of efficient infrared emitters, thermal energy devices, sensors, and photonic memory technologies."
Applications
The breakthrough could transform multiple fields: - Smart infrared sensors that can filter heat signals with precision - Thermal management systems that actively steer heat away from sensitive components - Directional energy conversion for more efficient solar and waste-heat harvesting - Photonic memory — storing information using light and heat instead of electrical charges
"Our ultimate goal is to develop compact devices that can actively control heat radiation, much like electronic circuits control the flow of electricity," said Prof. Koichi Okamoto, the project lead.
The research was published in the journal Laser & Photonics Reviews.
