Thermal disorder driven magnetic phases in van der Waals magnet CrI3

Abstract

Magnetic phase transitions often occur spontaneously at specific critical temperatures and are instrumental to understand the origin of long-range spin order in condensed matter systems. The presence of more than one critical temperature (T c ) has been observed in several compounds [1][2][3][4][5] where the coexistence of competing magnetic orders highlights the importance of phase separation driven by different factors such as pressure, temperature and chemical composition. However, it is unknown whether recently discovered two-dimensional (2D) van der Walls (vdW) magnetic materials 6,7 show such intriguing phenomena that can result in

Magnetic field effect on topological spin excitations in CrI$_3$

“…Even in the bulk samples, the surface layers are reported to have AF monoclinic structure that can be tuned by a c axis aligned magnetic field of a few Tesla [39]. While these results indicate minor energy differences in rhombohedral and monoclinic structures of CrI 3 , they suggest that the Cr honeycomb lattice may have subtle NN inversion symmetry breaking structural distortions that are responsible for the observed Dirac spin gap [56].…”

“…Whereas both bonds are bisected by the structural inversion centers, respectively, the interlayer AF exchange coupling J c1 will favor a breaking of the inversion symmetry between the two Cr sublattice spins. As a result, if the two Cr 3+ ions within a unit cell have spins of unequal moments (due to environmental defects such as Cr and/or I vacancy) [56], an energy gap will appear at the Dirac points without significantly affecting spin waves at other wave vectors.…”