In: Physical Review B, 2021, vol. 103, no. 12, p. L121103
With infrared spectroscopy, we studied the bulk electronic properties of the topological antiferromagnet MnBi2Te4 with TN ≃ 25 K. With the support of band-structure calculations, we assign the intra- and interband excitations and determine the band gap of Eg ≈ 0.17 eV. We also obtain evidence for two types of conduction bands with light and very heavy carriers. The multiband free-carrier...
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In: Physical Review Letters, 2019, vol. 122, no. 21, p. 217002
By means of infrared spectroscopy, we determine the temperature-doping phase diagram of the Fano effect for the in-plane Fe-As stretching mode in Ba1−xKxFe2As2. The Fano parameter 1=q2, which is a measure of the phonon coupling to the electronic particle-hole continuum, shows a remarkable sensitivity to the magnetic and structural orderings at low temperatures. Most strikingly, at elevated...
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In: Physical Review B, 2018, vol. 98, no. 20, p. 205111
We report resistivity, magnetization, and optical spectroscopy study on single-crystal sample of Sr3(Ru0.985Fe0.015 )2O7. An upturn is observed in resistivity at about 30 K. Below 30 K, the dip in resistivity R(ω), the suppression in scattering rate 1/τ (ω), the peaklike feature in optical conductivity σ1(ω), and the remainder of spectral weight all suggest the formation of a pseudogap....
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In: Physical Review Letters, 2018, vol. 121, no. 18, p. 187401
We present an infrared spectroscopy study of ZrTe5, which confirms a recent theoretical proposal that this material exhibits a temperature-driven topological quantum phase transition from a weak to a strong topological insulating state with an intermediate Dirac semimetal state around Tp ≃ 138 K. Our study details the temperature evolution of the energy gap in the bulk electronic structure....
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In: Physical Review B, 2018, vol. 97, no. 19, p. 195110
We performed optical studies on CaFeAsF single crystals, a parent compound of the 1111-type iron-based superconductors that undergoes a structural phase transition from tetragonal to orthorhombic at Ts=121 K and a magnetic one to a spin density wave (SDW) state at TN=110 K. In the low-temperature optical conductivity spectrum, after the subtraction of a narrow Drude peak, we observe a...
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