Magnetic 2D materials and heterostructures have emerged as a significant area of research, expanding the range of phenomena that can be explored in two dimensions. The discovery of atomically thin magnetic crystals, such as CrI₃ and Fe₃GeTe₂, has filled a critical gap in the family of 2D materials, enabling the study of novel magnetic states and their interactions with other 2D materials. These materials offer unique opportunities for exploring magnetic properties, including the control of magnetic order via external fields and the creation of van der Waals heterostructures with new physical effects. Theoretical considerations highlight the importance of spin dimensionality in determining magnetic behavior. In 2D systems, the spin dimensionality (n) influences the critical temperature (Tc) and the nature of magnetic order. For example, the Ising model (n=1) and the XY model (n=2) describe different magnetic behaviors, with the Ising model showing a phase transition at finite temperatures due to anisotropy, while the XY model exhibits quasi-long-range order. The Heisenberg model (n=3) is relevant for isotropic systems. Experimental studies have confirmed the existence of magnetic order in 2D materials, with CrI₃ and Fe₃GeTe₂ being among the most studied. These materials exhibit ferromagnetic and antiferromagnetic behaviors, with their magnetic properties influenced by factors such as layer thickness, external fields, and doping. Gating techniques have been used to control the magnetic properties of these materials, demonstrating the ability to tune the Curie temperature and coercive field. The application of magnetic 2D materials in van der Waals heterostructures has led to the development of magnetic tunnel junctions and other devices. For example, Fe₃GeTe₂/hBN/Fe₃GeTe₂ junctions exhibit a significant spin-valve effect, while CrI₃ tunnel barriers show negative magnetoresistance due to antiferromagnetic coupling between layers. These findings highlight the potential of 2D magnetic materials in both fundamental research and technological applications.Magnetic 2D materials and heterostructures have emerged as a significant area of research, expanding the range of phenomena that can be explored in two dimensions. The discovery of atomically thin magnetic crystals, such as CrI₃ and Fe₃GeTe₂, has filled a critical gap in the family of 2D materials, enabling the study of novel magnetic states and their interactions with other 2D materials. These materials offer unique opportunities for exploring magnetic properties, including the control of magnetic order via external fields and the creation of van der Waals heterostructures with new physical effects. Theoretical considerations highlight the importance of spin dimensionality in determining magnetic behavior. In 2D systems, the spin dimensionality (n) influences the critical temperature (Tc) and the nature of magnetic order. For example, the Ising model (n=1) and the XY model (n=2) describe different magnetic behaviors, with the Ising model showing a phase transition at finite temperatures due to anisotropy, while the XY model exhibits quasi-long-range order. The Heisenberg model (n=3) is relevant for isotropic systems. Experimental studies have confirmed the existence of magnetic order in 2D materials, with CrI₃ and Fe₃GeTe₂ being among the most studied. These materials exhibit ferromagnetic and antiferromagnetic behaviors, with their magnetic properties influenced by factors such as layer thickness, external fields, and doping. Gating techniques have been used to control the magnetic properties of these materials, demonstrating the ability to tune the Curie temperature and coercive field. The application of magnetic 2D materials in van der Waals heterostructures has led to the development of magnetic tunnel junctions and other devices. For example, Fe₃GeTe₂/hBN/Fe₃GeTe₂ junctions exhibit a significant spin-valve effect, while CrI₃ tunnel barriers show negative magnetoresistance due to antiferromagnetic coupling between layers. These findings highlight the potential of 2D magnetic materials in both fundamental research and technological applications.