The
intrinsic magnetic topological materials Mn(Sb/Bi)2n+2Te3n+4 have attracted
extensive attention due to their topological quantum properties. Although,
the Mn–Sb/Bi antisite defects have been frequently reported
to exert significant influences on both magnetism and band topology,
their formation mechanism and the methods to manipulate their distribution
and concentration remain elusive. Here, we present MnSb2Te4 as a typical example and demonstrate that Mn–Sb
antisite defects and magnetism can be tuned by controlling the crystal
growth conditions. The cooling rate is identified as the primary key
parameter. Magnetization and chemical analysis demonstrate that a
slower cooling rate would lead to a higher Mn concentration, a higher
magnetic transition temperature, and a higher saturation moment. Further
analysis indicates that the Mn content at the original Mn site (MnMn, 3a site) varies more significantly with
the cooling rate than the Mn content at the Sb site (MnSb, 6c site). Based on experimental observations,
magnetic phase diagrams regarding MnMn and MnSb concentrations are constructed. With the assistance of first-principles
calculations, it is demonstrated that the Mn–Sb mixing states
primarily result from the mixing entropy and the growth kinetics.
The present findings offer valuable insights into defects engineering
for preparation of two-dimensional quantum materials.