Laser pulses align hidden electrical regions in a crystal

Overview

Updated 1 hour ago

Tiny islands of positive and negative charge sit inside a modified strontium titanate crystal. For decades, physicists argued about whether cooling the crystal creates those islands or simply lines up ones already there.

A team at Auburn University now has evidence for the second answer. Watching how the crystal changed light as it warmed and cooled, they saw the islands persist and then turn into a shared orientation.

The same group then did it on demand. A laser pulse aligned the islands at temperatures where they normally stay jumbled, and an optical measurement caught the pattern before it faded about a picosecond later.

Why it matters

Light, not wires, can now flip a crystal's internal electrical order for a trillionth of a second, a step toward faster memory.

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Key Indicators

~1 ps

Lifetime of laser-induced alignment

The ordered pattern lasted roughly one trillionth of a second before fading.

~1 year

Time spent refining the detection setup

The team rebuilt its optical system before it could reliably see the weak signal.

3 years

From first meeting to first paper

The collaboration began at a 2023 physics meeting and produced graduate student Mohamed Kandil's first publication.

Voices

Curated perspectives — historical figures and your fellow readers.

People Involved

Wencan Jin

Thomas and Jean Walter Endowed Associate Professor, Auburn University Department of Physics

Leads the Auburn group that reported the result

Mohamed Kandil

Graduate student, Auburn University Department of Physics

First author on the Physical Review Letters paper

Yasuhide Tomioka

Researcher at Japan's National Institute of Advanced Industrial Science and Technology, coauthor

Listed as coauthor on the paper

Isao H. Inoue

Researcher at Japan's National Institute of Advanced Industrial Science and Technology, coauthor

Listed as coauthor on the paper

Organizations Involved

Auburn University Department of Physics

University research department

Home institution of the study

The Auburn lab built the optical measurement system and ran the laser experiments on the crystals.

National Institute of Advanced Industrial Science and Technology

Government research institute, Japan

Produced the crystals used in the experiment

The Japanese institute grew the specialized strontium titanate crystals the Auburn team could not make itself.

Timeline

March 2023 November 2026

3 events Latest: Yesterday

November 2026
Auburn reports picosecond optical poling
Latest Publication

The findings were reported publicly. The paper in Physical Review Letters received an Editors' Suggestion designation.
Yesterday
2025
Kandil sees polar regions align under laser light
Discovery

After nearly a year of rebuilding the detection system, the team observed the crystal's disordered electrical regions lining up under illumination.
2025
March 2023
Auburn and Japanese researchers begin collaborating
Collaboration

Jin met scientists from Japan's advanced industrial research institute at the American Physical Society March Meeting. They could grow crystals his lab needed.
March 2023

Scenarios

Another lab reproduces picosecond optical poling

Possible Resolves by End of 2028

Discussed by: Auburn researchers, in their account of the work, frame the result as a method others can use rather than a one-off measurement

The claim rests on a faint optical signal from regions a few nanometres across. If an independent group can align polar nanoregions with light in a different ferroelectric metal and detect the pattern the same way, the effect stops being a single lab's result and becomes a technique.

Auburn holds the light-induced order past a nanosecond

Uncertain Resolves by Q2 2029

Discussed by: The Auburn team and outside commenters on ultrafast materials research, who treat lifetime as the main barrier to any application

One picosecond is far too short for memory or logic. The next threshold is extending the aligned state long enough to read and write it repeatedly. That requires either a different material or a different pulse scheme, and it is where similar light-induced phases have stalled before.

Optical poling becomes a working memory element

Unlikely Resolves by End of 2031

Discussed by: No group has published a device demonstration; this scenario marks the outer edge of what the researchers say the work could eventually enable

A practical device would need to write a bit with light, hold it, and read it back at room temperature across many cycles. Nothing in the current result shows any of those steps, and the picosecond lifetime works against all of them.

Historical Context

2 moments from history that rhyme with this story — and how they unfolded.

November 2019

Light-switched charge order in lanthanum tritelluride (2019)

MIT physicists Nuh Gedik and Anshul Kogar fired sub-picosecond laser pulses at lanthanum tritelluride, a layered metal whose electrons spontaneously form a wave of high and low density along one direction. The pulse erased that pattern and a new one appeared at right angles, a configuration never seen in the material before.

Then

The perpendicular pattern lasted a few picoseconds, then vanished and the original returned.

Now

The result gave researchers a working example of competing ordered states in a quantum material, where suppressing one state lets another briefly surface.

Why this matters now

It established the template Auburn is now working in: a laser creates an ordered electrical state that exists for picoseconds and can be watched as it disappears.

June 2019

Light-induced ferroelectric phase in strontium titanate (2019)

An MIT team led by Keith Nelson, Xian Li and Edoardo Baldini, working with Andrew Rappe's group at Penn, hit strontium titanate with very fast light pulses. The pulses pulled positively and negatively charged ions in opposite directions, pushing the nonpolar crystal into a polar structure.

Then

The material took on ferroelectric character, the ability to separate positive and negative charge, only while driven by the light.

Now

The experiment showed that properties normally set by chemistry or temperature can be switched optically on trillionth-of-a-second timescales.

Why this matters now

It used the same base material as the Auburn work and the same goal, turning on electrical polarization with light instead of electrodes. Auburn's contribution is doing it in a metal and showing the underlying islands already exist.