## 1 Introduction
It should be noted that nanocrystalline CVD diamond films usually contain up to 1-2 at.% of hydrogen located at intercrystalline boundaries, which may be a piece of evidence in favor of the \"hydrogen\" model of magnetism in irradiation-modified diamonds. In the case of pure diamond, [PERSON] et al. [23] reported the existence of ferromagnetic hysteresis at room temperature in the magnetization of nanograins of diamond after nitrogen and carbon irradiation. Ferromagnetism with a Curie temperature of about 500 K was discovered in ultrathin layers of so-called Q-carbon with a predominantly amorphous structure [24; 25; 26], which is formed during the melting and rapid cooling of a carbon film after exposure to nanosecond laser pulses. The fraction of sp\({}^{3}\) carbon in Q-carbon is from 75 to 85%, and the remaining carbon atoms are sp\({}^{2}\) hybridized [24]. Ferromagnetism in a carbon film deposited in a radio frequency discharge was confirmed by measurements on a SQUID magnetometer [27] and explained by changes in the sp\({}^{2}\)/sp\({}^{3}\) carbon ratio. Carbon microspheres with a diameter of about 3 \(\upmu\)m containing graphitized nanocrystals with a thickness of 5-15 layers of graphene were obtained by pyrolysis, which exhibits ferromagnetic properties [28]. Magnetic ordering was observed in graphite and graphene oxide as a result of implantation with 100 MeV gold ions [29], as well as upon implantation of highly oriented pyrolytic graphite (HOPG) separately with carbon and hydrogen ions [30]. It is reported [31] on the production of pyrolytic magnetic carbon with the concentration of uncompensated electron spins of (3.5 \(\pm\) 0.7) \(\times\) 10\({}^{15}\) spins/mg. Magnetic ordering at room temperature was also obtained for polyaniline composites containing carbon quantum dots [32]. Due to high processability, studies of the magnetic properties of laser-graphitized films are of special interest. The observation of a stable ferromagnetic response at a temperature of 300 K from a 20 nm thick surface layer formed in the cut region of diamond crystal by a laser (wavelength 532 nm, energy 0.5 mJ, pulse duration 200 ns at the frequency of 15 kHz) is reported [33]. In this case, the magnetic moment measured by the SQUID magnetometer was observed only for crystals that were cut by a laser along the (100) surface orientation. The magnetic signals were much weaker for (110) and negligible for (111) laser-cut diamond surfaces. The dependence of the structure of the laser-graphitized layer on the crystallographic orientation of the diamond surface was previously discovered in [34; 35]. The ferromagnetic signal (coercive fields \(\approx\) 8 mT) disappeared after chemical etching or after moderate temperature annealing. According to [33], the results indicate that laser processing of diamond can lead to the creation of ferromagnetic spots on its surface. This phenomenon can be of interest not only for memory devices but also for other rather subtle applications [36; 37; 38; 39], such as using a localized magnetic spot near a nitrogen-carbon vacancy (NV-center) to influence its magneto-optical response, especially to increase its field sensitivity at certain applied field ranges. The processability of this approach arises from the ability of laser radiation to locally form NV centers in the volume of diamond samples [38; 39; 40]. Current understanding about the mechanisms of ferromagnetism of pure carbon materials is actively developing. Various causes capable of inducing a magnetic state in pure carbon systems have been considered: defects in the crystal lattice [8; 12], band ferromagnetism [41], and negatively curved sp\({}^{2}\)-bonded nanoregions in carbon structures [42], vacancy-hydrogen complexes [43], hydrogen passivated vacancies in graphene [44], etc. To explain ferromagnetism in graphite irradiated with high-energy protons, models based on the formation of networks of point defects due to grain boundaries [45] or high concentrations of vacancies [46] were proposed in [3].