研究目的
To study the band structure of twinned and detwinned BaFe2As2 using angle-resolved photoemission spectroscopy to identify the complex reconstructed band structure in the ordered state, including nematic splitting and magnetic folding effects.
研究成果
The study achieved a complete band assignment for BaFe2As2 in both normal and ordered states, observing nematic splitting of dxz and dyz orbitals and magnetic folding. A momentum-dependent nematic splitting of approximately 100 meV was found near the Brillouin zone corner. The high-quality data and comprehensive measurements along multiple directions provided a detailed understanding of the band structure, with implications for other iron-based superconductors.
研究不足
The influence of spin-orbit coupling and SDW gaps makes it challenging to precisely determine the momentum dependence of nematic band splitting. The surface sensitivity of ARPES may affect measurements due to potential surface contamination or reconstructions.
1：Experimental Design and Method Selection:
Angle-resolved photoemission spectroscopy (ARPES) was used to study the band structure. Measurements were conducted in both ordered (20 K) and normal (150 K) states along four high-symmetry momentum directions (Γ-X, Γ-Y, Z-X, Z-Y) for twinned and detwinned samples. Linear horizontal (LH) and linear vertical (LV) polarizations were employed to probe different orbital characters.
2：Sample Selection and Data Sources:
High-quality single crystals of BaFe2As2 were grown using a self-flux method. Samples were cleaved in situ below 30 K. Data were collected at the Stanford Synchrotron Radiation Lightsource beamline 5-
3：List of Experimental Equipment and Materials:
ARPES setup at beamline 5-2, piezoelectric detwinning device, single crystals of BaFe2As2, photon energy of 47 eV, energy resolution better than 12 meV, angular resolution of 0.1°, base pressure below 5×10^{-11} Torr.
4：1°, base pressure below 5×10^{-11} Torr.
Experimental Procedures and Operational Workflow:
4. Experimental Procedures and Operational Workflow: Samples were mounted and detwinned using a piezoelectric device applying compressive uniaxial pressure. ARPES spectra were acquired with LH and LV polarizations. Measurements were performed at specific temperatures and momentum cuts, with data processed using second derivatives to highlight band dispersions.
5：Data Analysis Methods:
Band dispersions were analyzed using energy distribution curves (EDCs) and second derivatives. A tight-binding model was used for band assignment, and comparisons were made with previous studies and theoretical predictions.
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