Coherent longitudinal acoustic phonons in pyrite

Kasami, M.; Mishina, Tomobumi; Yamamoto, S.; Nakahara, J.

doi:10.1016/j.jlumin.2004.01.062

Cited by 7 publications

(5 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Aside from significant differences in signal magnitudes, this general description of the response applies for all four of the pump wavelengths including the 0.58 eV, which lies well below the accepted band gap energy of pyrite. Finally, there are oscillations apparent in the time dynamics of the low-energy probe region with a period of around 8 ps, which corresponds to the longitudinal acoustic phonon reported by Kasami et al 46 Similar data for each of the pump energies are contained in the Supporting Information as well as a more detailed analysis of the oscillations. Regarding the analysis of the time dynamics, we stress that relating exponential fits at a particular wavelength to populations in a particular state is a very delicate matter.…”

supporting

confidence: 70%

“…Despite this apparent benefit such experiments, to our knowledge, have yet to be reported. There are three instances of transient reflection of pyrite in the literature of which we are aware; 11,25,46 however, all were single pump, single probe wavelength measurements and reveal only a small portion of the picture of the contributing states. In this paper we will present the transient reflection of pyrite using several pump energies and a visible broadband continuum probe along with a discussion relating these results to the current knowledge of the density of states and defects.…”

Section: ■ Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Electronic Dynamics in Natural Iron Pyrite Studied by Broadband Transient Reflection Spectroscopy

2016

View full text Add to dashboard Cite

Iron pyrite (FeS2) is an abundant natural mineral with interesting physical and chemical properties, including its near IR bandgap and extremely high absorption coefficient throughout the visible range. The dynamics of photoinitiated carriers and their interactions with intrinsic and surface defects are still not fully understood, yet clearly are responsible for pyrite’s underwhelming photovoltaic and photocatalytic performance. Here we report, to our knowledge for the first time, broadband ultrafast transient reflection from single-crystal natural iron pyrite with several excitation wavelengths both higher and lower than the accepted nominal bandgap of pyrite. We also demonstrate a method to transform transient reflection to transient absorption, without requiring any assumptions regarding the magnitude of either the absorption coefficient or the refractive index, allowing for a more direct interpretation of our results. An important finding from this work is the observation of a long-lived weak signal when pumping with 0.58 eV, an energy well below the accepted bandgap, which may be evidence for direct optical excitation of either intrinsic trailing edges of the bands or midgap defect states. We identify that after approximately 10 ps the transient spectra due to pumping at 2.59, 1.58, and 0.91 eV all appear qualitatively similar, suggesting relaxation to a common carrier distribution. This common distribution appears to decay on two time scales of about 30 and ≫200 ps. Our results should play a role in understanding charge carrier dynamics within the intricate and complex band structure of pyrite and hopefully provide clarification and direction for future efforts in the development of iron pyrite based technologies.

show abstract

supporting

confidence: 70%

Section: ■ Introductionmentioning

confidence: 99%

Electronic Dynamics in Natural Iron Pyrite Studied by Broadband Transient Reflection Spectroscopy

2016

View full text Add to dashboard Cite

show abstract

“…Since the photoabsorbed energy is determined as 3.0 mJ/cm 2 from the optical reflectivity of 70 %, it is concluded that a large amount of the absorbed energy is converted into strain energy for the lattice, which is consistent with the X-ray experimental result [25]. It is well known that a strain pulse with a picosecond duration can be generated by irradiating a metal film or a semiconductor with intense femtosecond laser pulses and that it propagates into the sample [26][27][28]. Because our experimental conditions are very close to this situation, a strain pulse is also expected, and the lattice contraction corresponds to the initial stage of the strain pulse.…”

supporting

confidence: 70%

Softening Mechanism of Coherent Phonons in Antimony Under High Density Photoexcitation

Kumagai,

Matsubara,

Nakahara

et al. 2016

Preprint

Self Cite

View full text Add to dashboard Cite

We have investigated the dynamical properties of coherent phonons generated in antimony under high density photo excitation. Precise measurements and extended analysis of coherent phonon oscillations provide new insights into the process of impulsive softening. In the process of recovering from instantaneous softening, phonon frequency shows an unexpected temporal evolution involving an abrupt change and a slight overshoot. Moreover, fluence dependence of the initial phonon frequency is strongly correlated with the phonon frequency shift of the high-pressure Raman spectra.These results clearly prove that the structural changes (lattice contraction and expansion) induced by laser excitation governs the softening mechanism of coherent phonons.

show abstract

“…Here Θ ρ D is the transport Debye temperature. The Debye temperature for iron pyrite is 610 K 50 and we estimate the transport Debye temperature, Θ ρ D = 2hk F s/k B , where s is the speed of sound (8980 m/s), to be between 200 and 250 K 39,54 . To test if the resistivity we measure in Fe 1−x Co x S 2 can be described as being due to carrier scattering from phonons, we have fit the full Debye form to our data.…”

Section: Resistivity Above 20 Kmentioning

confidence: 99%

Kondo effect and absence of quantum interference effects in the charge transport of cobalt doped iron pyrite

Guo,

Young,

Macaluso

et al. 2009

Preprint

View full text Add to dashboard Cite

The Hall effect and resistivity of the carrier doped magnetic semiconductor Fe1−xCoxS2 were measured for 0 ≤ x ≤ 0.16, temperatures between 0.05 and 300 K, and fields of up to 9 T. Our Hall data indicate electron charge carriers with a density of only 10 to 30% of the Co density of our crystals. Despite the previous identification of magnetic Griffiths phase formation in the magnetic and thermodynamic properties of this system for the same range of x, we measure a temperature independent resistivity below 0.5 K indicating Fermi liquid-like transport. We also observe no indication of quantum corrections to the conductivity despite the small values of the product of the Fermi wave vector and the mean-free-path, 1.5 ≤ kF ℓ ≤ 15, over the range of x investigated. This implies a large inelastic scattering rate such that the necessary condition for the observation of quantum contributions to the carrier transport, quantum coherence over times much longer than the elastic scattering time, is not met in our samples. Above 0.5 K we observe a temperature and magnetic field dependent resistivity that closely resembles a Kondo anomaly for x less than that required to form a long range magnetic state, xc. For x > xc, the resistivity and magnetoresistance resemble that of a spin glass with a reduction of the resistivity by as much as 35% in 5 T fields. We also observe an enhancement of the residual resistivity ratio by almost a factor of 2 for samples with x ∼ xc indicating temperature dependent scattering mechanisms beyond simple carrier-phonon scattering. We speculate that this enhancement is due to charge carrier scattering from magnetic fluctuations which contribute to the resistivity over a wide temperature range.

show abstract

Coherent longitudinal acoustic phonons in pyrite

Cited by 7 publications

References 7 publications

Electronic Dynamics in Natural Iron Pyrite Studied by Broadband Transient Reflection Spectroscopy

Electronic Dynamics in Natural Iron Pyrite Studied by Broadband Transient Reflection Spectroscopy

Softening Mechanism of Coherent Phonons in Antimony Under High Density Photoexcitation

Kondo effect and absence of quantum interference effects in the charge transport of cobalt doped iron pyrite

Contact Info

Product

Resources

About