Abstract
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 ≲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.
Highlights
IntroductionSince the first studies on the magnetic order found in pure graphite-based samples were reported, see [1] and Refs
Reported the existence of ferromagnetic hysteresis at room temperature in the magnetization of nanograins of diamond after nitrogen and carbon irradiation. This interesting result was ascribed to structural modification or defects produced by the irradiation, a clear case of the phenomenon called defect-induced magnetism (DIM)
From the characterization of the impurities with particle-induced X-ray emission (PIXE), we conclude that the maximum magnetic impurity concentration was 2.6 ppm of Fe in sample 164
Summary
Since the first studies on the magnetic order found in pure graphite-based samples were reported, see [1] and Refs. Therein, the possibility of having magnetic order in other carbon-based compounds at room temperature and without doping with magnetic ions attracted the interest of the community. In case of pure diamond, Talapatra et al [2]. Reported the existence of ferromagnetic hysteresis at room temperature in the magnetization of nanograins of diamond after nitrogen and carbon irradiation. This interesting result was ascribed to structural modification or defects produced by the irradiation, a clear case of the phenomenon called defect-induced magnetism (DIM). Superconducting (with a transition temperature of Tc ∼ 3 K)
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