Spin defects in hexagonal boron nitride created by helium ion bombardment

Nationwide College of Singapore (NUS) physicists have developed a way utilizing a targeted beam of helium ions to create arrays of defects in hexagonal boron nitride (hBN) that may doubtlessly be used for magnetic sensing purposes.

Hexagonal boron nitride (hBN) is a two-dimensional (2D) materials comprising of boron and nitrogen atoms organized in a hexagonal lattice construction. It displays distinctive properties for purposes in quantum sensing. Many forms of defects have been found in hBN and considered one of them, the negatively charged boron emptiness (V_B^–), is of explicit curiosity because it possesses spin properties that make it worthwhile for quantum sensing purposes.

On this research, a beam of excessive vitality helium ions produced on the accelerator facility on the Middle for Ion Beam Purposes (CIBA) within the Division of Physics, NUS was used to irradiate flakes of hBN to generate V_B^– optical facilities. The power to focus the ion beam to nano-sized spots and to spatially scan the beam permits for patterned arrays of optical emitters to be fabricated with excessive precision.

The work is the results of a collaboration between a analysis crew led by Affiliate Professor Andrew Bettiol and the crew led by Affiliate Professor Goki Eda, each from the Division of Physics, NUS. The V_B^– optical defect middle which, was produced by way of the experiments run by the analysis crew, reveals some fascinating properties when it’s uncovered to microwave vitality. This research was revealed within the journal Superior Optical Supplies.

A spectroscopic approach referred to as Optically Detected Magnetic Resonance (ODMR) was used to sense tiny magnetic fields within the experiments. This method combines the rules of magnetic resonance and optical spectroscopy to check the properties of paramagnetic supplies and their interplay with electromagnetic radiation.

First, a inexperienced laser is used to excite the V_B^– defect middle in order that it emits mild at a wavelength of round 810 nm, which is within the close to infra-red a part of the electromagnetic spectrum. A copper antenna is then used to generate a particular microwave frequency close to the hBN pattern. This microwave vitality initializes the defect right into a spin state that leads to the discount within the mild depth emitted by the defect. The microwave frequency is tuned till a drop in mild depth is detected. This occurred at roughly 3.48 GHz, the place a double dip within the photoluminescence depth was noticed. As soon as the microwave resonance frequency is discovered, the sensor is prepared to be used to detect magnetic fields.

Prof Bettiol mentioned, “By utilizing this distinctive property exhibited by hBN, a tiny magnetic subject that generally happens in organic techniques or in magnetic supplies will shift the resonant frequency and this may trigger the sunshine emission from the sensor to be restored. The sunshine emission from the V_B^– optical defect middle supplies a method of optically detecting the native magnetic subject.”

Prof Eda added, “hBN is a flexible materials that may be readily built-in into on-chip gadgets. Our demonstration to create spin defects in hBN with excessive precision is a vital step in the direction of realizing on-chip magnetic sensors.”