Nanometers-Thick Ferromagnetic Surface Produced by Laser Cutting of Diamond

In this work, we demonstrate that cutting diamond crystals with a laser (532 nm wavelength, 0.5 mJ energy, 200 ns pulse duration at 15 kHz) produced a less than or similar to 20 nm thick surface layer with magnetic order at room temperature. We measured the magnetic moment of five natural and six CVD diamond crystals of different sizes, nitrogen contents and surface orientations with a SQUID magnetometer. A robust ferromagnetic response at 300 K was observed only for crystals that were cut with the laser along the (100) surface orientation. The magnetic signals were much weaker for the (110) and negligible for the (111) orientations. We attribute the magnetic order to the disordered graphite layer produced by the laser at the diamond surface. The ferromagnetic signal vanished after chemical etching or after moderate temperature annealing. The obtained results indicate that laser treatment of diamond may pave the way to create ferromagnetic spots at its surface.

Automated summary

In this study, we demonstrated that cutting diamond crystals with a laser can produce a magnetic ordered layer at the surface with a thickness of less than or similar to 20 nm. The ferromagnetic response was observed only when the crystals were cut along the (100) surface orientation. The magnetic order is attributed to the disordered graphite layer produced by the laser on the diamond surface, and it can be eliminated by chemical etching or moderate temperature annealing.