On the nature of the carriers in ferromagnetic FeSe

Wu, Xianxin; Shen, Dezhen; Zhang, Z. Z.; Zhang, J. Y.; Liu, K. W.; Li, B. H.; Lu, Yaojie; Ye, Bin; Zhao, Dongxu; Li, Baosong; Shan, Chengwei; Fan, Xiaowu; Liu, H. J.; Yang, Chunlei

doi:10.1063/1.2712497

Cited by 39 publications

(19 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…52 The fluences of the pump and probe beams were 39.7 and 2.3 µJ/cm 2 , respectively. The pump pulses have a corresponding photon energy of 3.1 eV at which greater absorption occurred in the absorption spectrum of FeSe, 53 and hence generate electronic excitation. To study the QP dynamics, we measured the photoinduced reflectivity (ΔR/R) transients of the probe beam with photon energy 1.55 eV.…”

Section: Methodsmentioning

confidence: 99%

Unveiling the hidden nematicity and spin subsystem in FeSe

et al. 2017

View full text Add to dashboard Cite

The nematic order (nematicity) is considered as one of the essential ingredients to understand the mechanism of Fe-based superconductivity. In most Fe-based superconductors (pnictides), nematic order is reasonably close to the antiferromagnetic order. In FeSe, in contrast, a nematic order emerges below the structure phase transition at T s = 90 K with no magnetic order. The case of FeSe is of paramount importance to a universal picture of Fe-based superconductors. The polarized ultrafast spectroscopy provides a tool to probe simultaneously the electronic structure and the magnetic interactions through quasiparticle dynamics. Here we show that this approach reveals both the electronic and magnetic nematicity below and, surprisingly, its fluctuations far above T s to at least 200 K. The quantitative pump-probe data clearly identify a correlation between the topology of the Fermi surface and the magnetism in all temperature regimes, thus providing profound insight into the driving factors of nematicity in FeSe and the origin of its uniqueness.

show abstract

Section: Methodsmentioning

confidence: 99%

Unveiling the hidden nematicity and spin subsystem in FeSe

et al. 2017

View full text Add to dashboard Cite

show abstract

“…The PbO-type α-FeSe 1−x compound is the one of current interest and has been studied extensively for its spintronics-related magnetic properties by Shen and coworkers, [7,8,9,10] who concluded from observed hysteresis a ferromagnetic (FM) state in the nonstoichiometric phase, but a nonmagnetic state in the stoichiometric phase. Very recently, Hsu et al reported superconductivity with T c = 8 K, at x = 0.12 and 0.18.…”

Section: Introductionmentioning

confidence: 99%

Magnetism driven by anion vacancies in superconductingα-FeSe1−x

2008

View full text Add to dashboard Cite

To study the microscopic electronic and magnetic interactions in the substoichiometric iron chalcogenide FeSe1−x which is observed to superconduct at x ≈ 1 8 up to Tc=27 K, we use first principles methods to study the Se vacancy in this nearly magnetic FeSe system. The vacancy forms a ferrimagnetic cluster of eight Fe atoms, which for the ordered x= 1 8 alloy leads to half metallic conduction. Similar magnetic clusters are obtained for FeTe1−x and for BaFe2As2 with an As vacancy, although neither of these are half metallic. Based on fixed spin density results, we suggest the low energy excitations in FeSe1−x are antiparamagnon-like with short correlation length.

show abstract

“…The fluences of the pump beam and the probe beam are 9.92 and 1.40 µJ/cm 2 , respectively. The pump pulses have corresponding photon energy (3.1 eV) where the higher absorption occurred in the absorption spectrum of FeSe [9] and hence can generate electronic excitations. The QP dynamics is studied by measuring the photoinduced transient reflectivity changes (∆R/R) of the probe beam with photon energy of 1.55 eV.…”

mentioning

confidence: 99%

“…The energy of the acoustic wave is E phonon = ω phonon = q phonon v s = 2nv s k probe cos(θ i ), where v s is the sound velocity along normal direction of crystal surface. Using λ probe = 800 nm, n probe = 2 [9], θ i = 2. km/s [25], the phonon energy, E phonon , is calculated to be 0.077 meV, which is very close to the result, 0.087 meV, directly obtained from the above ∆R/R measurements. We further investigate the temperature dependence of the LA phonon energy as shown in Fig.…”

mentioning

confidence: 99%

Quasiparticle Dynamics and Phonon Softening in FeSe Superconductors

Luo

Cheng

et al. 2012

Phys. Rev. Lett.

View full text Add to dashboard Cite

Quasiparticle dynamics of FeSe single crystals revealed by dual-color transient reflectivity measurements (∆R/R) provides unprecedented information on Fe-based superconductors. The amplitude of the fast component in ∆R/R clearly gives a competing scenario between spin fluctuations and superconductivity. Together with the transport measurements, the relaxation time analysis further exhibits anomalous changes at 90 and 230 K. The former manifests a structure phase transition as well as the associated phonon softening. The latter suggests a previously overlooked phase transition or crossover in FeSe. The electron-phonon coupling constant λ is found to be 0.16, identical to the value of theoretical calculations. Such a small λ demonstrates an unconventional origin of superconductivity in FeSe. , tremendous experimental and theoretical effort has been devoted to exploring their characteristics. These Fe-based pnictide compounds exhibit a very interesting phase diagram, with antiferromagnetism (or spin-density wave) at low doping and superconductivity at intermediate doping [2]. The simultaneous presence of magnetism and superconductivity in the phase diagram implies that magnetism plays an important role in the superconductivity mechanism. The existence of precursor superconductivity above T c which competes with the spin-density wave order [3], and a pseudogaplike feature with onset around 200 K [4] were observed on underdoped (Ba, K)Fe 2 As 2 and nearly optimally doped SmFeAsO 0.8 F 0.2 , respectively. Additionally, a coherent lattice oscillation was also found in Co-doped BaFe 2 As 2 using time-resolved pump-probe reflectivity with 40 fs time resolution [5]. Among various FeSCs, the iron chalcogenide FeSe [6] stands out due to its structure simplicity, which consists of iron-chalcogenide layers stacking one by another with the same Fe +2 charge state as the iron pnictides. This so-called "11" system is so simple that it could be the key structure to understanding the origin of high-T c superconductivity [7]. There has been considerable concern over the interplay between electronic structure, phonons, magnetism, and superconductivity in 11-type FeSe. Therefore, further studies of their quasiparticle dynamics are indispensable to understanding the high-T c mechanism in FeSCs. Here we report the first time-resolved femtosecond spectroscopy study of FeSe single crystals to elucidate the electronic structure and the quasiparticle (QP) dynamics.In this study, FeSe single crystals were grown in evacuated quartz ampoules using a KCl/AlCl 3 flux [8]. The crystalline structure of the samples was examined by xray diffraction. The superconducting transition temperature T c of the FeSe single crystal was determined to be 8.8 K by the middle point of the resistive transition. The femtosecond spectroscopy measurement was performed using a dual-color pump-probe system (for light source, the repetition rate: 5.2 MHz, the wavelength: 800 nm, and the pulse duration: 100 fs) and an avalanche photodetector with the standard lock-in te...

show abstract

On the nature of the carriers in ferromagnetic FeSe

Cited by 39 publications

References 13 publications

Unveiling the hidden nematicity and spin subsystem in FeSe

Unveiling the hidden nematicity and spin subsystem in FeSe

Magnetism driven by anion vacancies in superconductingα-FeSe1−x

Quasiparticle Dynamics and Phonon Softening in FeSe Superconductors

Contact Info

Product

Resources

About