Two-dimensional hybrid metal halide device allows control of terahertz emissions

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Two-dimensional hybrid metal halidides have been used by researchers to control the direction of terahertz radiation produced by spintronic schemes. This device is smaller, lighter, and cheaper to make than traditional terahertz generators.

Terahertz (THz), also known as the electromagnetic spectrum, is the frequency range between 100 GHz to 10 THz. THz technologies are promising for applications that include faster computing, communications, and sensitive detection equipment. It has been difficult to create reliable THz devices due to their cost, inefficiency, and size.

Dali Sun, assistant professor at North Carolina State University in Physics and co-author of the study, says that THz devices should be light, inexpensive, and strong. We found that a 2-D hybrid of metal halides and spintronics could meet many of these requirements.

This 2-D hybrid metal-halide is a commercially available and popular synthetic hybrid semiconductor called butyl ammonium led iodine. Spintronics is the control of electron spin, not just its charge. This allows for energy creation.

Sun and his colleagues at Argonne National Laboratories and the University of North Carolina Chapel Hill, and Oakland University designed a device that layered 2-D hybrid metal halides and a ferromagnetic material, and then excited it with a laser to create an ultrafast spin current, which in turn generates THz radiation.

The 2-D hybrid hybrid metal halide device performed better than larger, heavier, and more expensively produced THz emitters. They also discovered that its properties made it possible to control the direction of THz transmission.

Sun explains that traditional terahertz transmitters relied on ultrafast photocurrent. "But spintronic-generated emission produces a wider bandwidth THz frequency. The direction of THz emission can also be controlled by changing the speed of laser pulses and the direction magnetic field. This affects the interaction between magnons and photons and gives us directional control."

Sun believes this work could be a step towards exploring 2-D hybrid metal-halide materials in spintronic applications.

Sun states that the 2-D hybrid metal-halide-based device used in this case is smaller, more cost-effective to produce, and can withstand higher temperatures. Sun says this suggests that 2-D hybrid halide materials could be superior to conventional semiconductor materials used for THz applications. These materials require more complex deposition techniques that are more vulnerable to defects.

"We hope our research will lead to a promising testbed for the design of a wide range of low-dimensional hybrid metal-halide materials for future solution based spintronic or spin-optoelectronic uses."

Nature Communications publishes the work.

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Kankan Cong et al., Coherent Control of Asymmetric Spintronic Terahertz Emission from Two-dimensional Hybrid Metal Halides, Nature Communications (2021). Information from Nature Communications Kankan Cong et al., Coherent Control of Asymmetric Spintronic Terahertz Emission From Two-dimensional Hybrid Metal Halides. (2021). DOI: 10.1038/s41467-021-26011-6

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