Supreme enhancement of ferromagnetism in a spontaneous-symmetry-broken 2D nanomagnet

The ability to tune and control the magnetic phases of two-dimensional (2D) nanomagnets at room temperature is indispensable for the development of future spintronics and low-dimensional spin circuits. In this work, a first-principles-based investigation combined with a Monte Carlo simulation based on a 2D Ising model is used to investigate the electronic and magnetic behaviour of a recently discovered 2D material, Cr2Ge2Se6 over a large range of strain and electric field strength. This material offers ferromagnetic -> antiferromagnetic and semiconductor -> metallic phase transitions in different regimes. In the presence of strain, a colossal enhancement of the critical temperature (T-c) is observed, from 149 K to 885 K. The application of an electric field allows a further enhancement of the T-c to a value of 919 K, offering a supreme enhancement (similar to 517%), compared to its natural condition. The origin of this behavior can be traced to a super-exchange interaction between the Cr and Se atoms and the intrinsic magnetic anisotropy of Cr2Ge2Se6. The presence of external stimuli engenders spontaneous symmetry breaking with an enhanced magnetic moment (similar to 4.36 mu B/Cr atom), a significant intrinsic spin polarisation (similar to 100%) in a half-metallic regime, and a very high critical temperature. The insights of the current investigation could be useful for future developments in multi-stimuli-assisted room-temperature ferromagnetism and electronic phase control, which are of great significance for future magneto-electronic applications.