Pressure-Tuned Intralayer Exchange in Superlattice-Like MnBi<sub>2</sub>Te<sub>4</sub>/(Bi<sub>2</sub>Te<sub>3</sub>)<i><sub>n</sub></i> Topological Insulators.
basic_science · Level V
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- Record sourced from PubMed, PMID 34197120.
- Also identified by DOI 10.1021/acs.nanolett.1c01874.
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Abstract
The magnetic structures of MnBi<sub>2</sub>Te<sub>4</sub>(Bi<sub>2</sub>Te<sub>3</sub>)<sub><i>n</i></sub> can be manipulated by tuning the interlayer coupling via the number of Bi<sub>2</sub>Te<sub>3</sub> spacer layers <i>n</i>, while the intralayer ferromagnetic (FM) exchange coupling is considered too robust to control. By applying hydrostatic pressure up to 3.5 GPa, we discover opposite responses of magnetic properties for <i>n</i> = 1 and 2. MnBi<sub>4</sub>Te<sub>7</sub> stays at A-type antiferromagnetic (AFM) phase with a decreasing Néel temperature and an increasing saturation field. In sharp contrast, MnBi<sub>6</sub>Te<sub>10</sub> experiences a phase transition from A-type AFM to a quasi-two-dimensional FM state with a suppressed saturation field under pressure. First-principles calculations reveal the essential role of intralayer exchange coupling from lattice compression in determining these magnetic properties. Such magnetic phase transition is also observed in 20% Sb-doped MnBi<sub>6</sub>Te<sub>10</sub> because of the in-plane lattice compression.