55 research outputs found
Fabrication of Polymeric Ultrafiltration Membranes Using Ionic Liquids as Green Solvents
Ph.DDOCTOR OF PHILOSOPH
Tunable dynamical magnetoelectric effect in antiferromagnetic topological insulator MnBiTe films
More than forty years ago, axion was postulated as an elementary particle
with a low mass and weak interaction in particle physics to solve the strong
(charge conjugation and parity) puzzle. Axions are also
considered as a possible component of dark matter of the universe. However, the
existence of axions in nature has not been confirmed. Interestingly, axions
arise as pseudoscalar fields derived from the Chern-Simons theory in condensed
matter physics. In antiferromagnetic insulators, the axion field can become
dynamical induced by spin-wave excitations and exhibits rich exotic phenomena,
such as, the chiral magnetic effect, axionic polariton and so on. However, the
study of the dynamical axion field is rare due to the lack of real materials.
Recently, MnBiTe was discovered to be an antiferromagnetic topological
insulator with a quantized axion field protected by the inversion symmetry
and the magnetic-crystalline symmetry . Here, we
studied MnBiTe films in which both the and
symmetries are spontaneously broken and found that the dynamical axion field
and largely tunable dynamical magnetoelectric effects can be realized through
tuning the thickness of MnBiTe films, the temperature and the element
substitution. Our results open a broad avenue to study axion dynamics in
antiferromagnetic topological insulator MnBiTe and related materials,
and also is hopeful to promote the research of dark matter.Comment: 6 pages, 4 figure
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