Kavli Affiliate: Gang Su
| First 5 Authors: Xiang Li, Xiang Li, , ,
| Summary:
The pursuit of high-temperature quantum anomalous Hall (QAH) insulators faces
fundamental challenges, including narrow topological gaps and low Curie
temperatures ($T_textC$) in existing materials. Here, we propose a
transformative strategy using bilateral hydrogenation to engineer a robust QAH
state in the topologically trivial ferromagnetic semiconductor
Cr$_text2$Ge$_text2$Te$_text6$. First-principles calculations
reveal that hydrogenation induces a topological phase transition in
Cr$_text2$Ge$_text2$Te$_text6$ by shifting its Dirac
points-originally embedded in the conduction bands-to the vicinity of the Fermi
level in Cr$_text2$Ge$_text2$Te$_text6$H$_text6$. This
electronic restructuring, coupled with spin-orbit coupling, opens a global
topological gap of 118.1 meV, establishing a robust QAH state with Chern number
$C=$ 3. Concurrently, hydrogenation enhances ferromagnetic superexchange via
the $d_z^2$-$p_z$-$d_xz$ channel, significantly strengthening the
nearest-neighbor coupling $J_text1$ by 3.06 times and switching
$J_text2$ from antiferromagnetic to ferromagnetic. Monte Carlo simulations
predict a high $T_textC$ = 198 K, sustained well above liquid nitrogen
temperature and far exceeding pristine
Cr$_text2$Ge$_text2$Te$_text6$ (28 K). This work establishes
surface hydrogenation as a powerful route to simultaneously control topology
and magnetism in 2D materials, unlocking high-temperature QAH platforms for
dissipationless spintronic applications.
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