Open AccessМеханизм открытия щели в точке Дирака в электронном спектре Gd-допированного топологического изолятора
Author(s) -
А.М. Шикин,
Д.А. Естюнин,
А.В. Королева,
Д.А. Глазкова,
Т.П. Макарова,
С.О. Фильнов
Publication year - 2020
Publication title -
fizika tverdogo tela
Language(s) - English
Resource type - Journals
eISSN - 1726-7498
pISSN - 0367-3294
DOI - 10.21883/ftt.2020.02.48881.589
Subject(s) - angle resolved photoemission spectroscopy , condensed matter physics , synchrotron radiation , antiferromagnetism , paramagnetism , physics , dirac fermion , photoemission spectroscopy , x ray photoelectron spectroscopy , electronic structure , fermion , nuclear magnetic resonance , quantum mechanics
The electronic structure of magnetically-doped TI with stoichiometry Bi1.09Gd0.06Sb0.85Te3in the region of the Dirac point has been studied in detail by angle-resolved photoelectronspectroscopy (ARPES) at various temperatures (above and below the Néel temperature, 1-35 K)and different polarizations of synchrotron radiation. It has shown that the energy gap inphotoemission spectra opens at the Dirac point and remains open above the temperature of thelong-range magnetic ordering, Tn. Measurements of magnetic properties by the superconductingmagnetometry method (SQUID) have shown antiferromagnetic ordering with a transitiontemperature to the paramagnetic phase equal to 8.3 K. Study of the temperature dependence ofthe Dirac cone state intensity at the Г point by ARPES has confirmed the magnetic transitionand has shown a possibility of its indication directly from photoemission spectra. A moredetailed analysis of the splitting between the upper and lower Dirac cone states (i.e. the energygap) at the Dirac point in the photoelectron spectra has shown the dependence of the measuredgap on the synchrotron radiation polarization (about 28-30 meV for p-polarization and 22-25meV for circularly polarized radiation of opposite chirality). The mechanism of opening the gapat a Dirac point above the Tn was proposed due to the “pairing” of the Dirac fermions withopposite momentum and spin orientation as a result of their interaction with the spin texturegenerated by photoemission in the region of the photoemission hole on a magnetic impurity atom(Gd). It was shown that the gap at the Dirac point, measured above Tn, is dynamic and is formeddirectly during photoemission process. At the same time, the origin of the gap remains magnetic(even when the long-range magnetic ordering is destroyed) and is associated with the propertiesof the magnetic topological insulator that determines a practically unchanged size of the gapabove Tn. The dynamic origin of the generated gap is confirmed by the dependenceof its magnitude on the polarization of synchrotron radiation.