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Laser flashes reveal a new, "hidden" state of matter in the crystal



A new phase of matter hiding in a crystal is discovered after physicists have blown the crystal with ultra-short pulses of laser light.

A fleeting new phase of matter appeared in a crystalline material called lanthanum tritelluride – composed of one lanthanum atom and three tellurium atoms. The ultra-short laser pulses changed how the electrons moved through the crystal, and the change was sufficient to classify it as an entirely new state of matter.

Energy bursts usually make substances less ordered, such as ice that melts into heat or glass, which shatters a crack, physicists say. But in this case, the laser flash seems to move the crystal in a rare state in a higher order.

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"Usually to change the phase of a material you are trying to chemically change, or pressure, or magnetic fields. In this work, we use light to make these changes, "said MIT physicist Nuh Gedik, one of the experiment's leaders, said in a statement,

Lanthanum Tritelluride crystals naturally form a layered structure, said physicists. And in this layered structure you will find an unusual pattern.

In most substances, the electrons are fairly evenly distributed. But at very low temperatures, lanthanum tritelluride forms pockets with low electron density and pockets with high electron density. And these pockets are organized in a flat pattern that points in the same direction as the crystal layers. Physicists call this model the charge density wave.

But hit a crystal with a flash of laser light less than a trillionth of a second, and the charge density wave sharply (and very briefly) will switch directions ̵

1; flowing perpendicular to the direction it originally flowed. This is the new phase of matter discovered by physicists.

In theory, the new phase of matter that appears after the laser flash exists as a latent possibility in the crystal at all times. Laser light suppresses the dominant phase – this original stream of electric charge – and allows the hidden phase to appear.

When the effect of the laser disappears, the initial phase solidifies. The researchers called the two phases "competing states" in the crystal.

And there are probably other competing states that lie in other crystalline substances, according to researchers in a paper published November 11 in the journal Nature Physics. And they can also be detected with flashes of laser light. Given time, the researchers said, they can find new ways to manipulate materials with nothing but flashing lights.

Originally published on by Live Science .

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(Credit image: Future plc)


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