Optical phonons in the reflectivity spectrum of FeSi

Damascelli, A.; Schulte, Karl‐Wilhelm; Marel, D. van der; Fäth, M.; Menovsky, A.A.

doi:10.1016/s0921-4526(96)00840-x

Cited by 13 publications

(12 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Similar temperature dependence properties were reported, instead, for the narrow-gap semiconductor FeSi: at low temperature FeSi is a paramagnetic insulator but it develops a pseudogap associated with a bad-metal state as temperature increases [36][37][38]. This anomalous behavior is explained well by spin fluctuations in the context of the theory of itinerant magnetism elaborated by Moriya [39].…”

supporting

confidence: 80%

Lifshitz transition driven by spin fluctuations and spin-orbit renormalization inNaOsO3

et al. 2016

View full text Add to dashboard Cite

In systems where electrons form both dispersive bands and small local spins, we show that changes of the spin configuration can tune the bands through a Lifshitz transition, resulting in a continuous metal-insulator transition associated with a progressive change of the Fermi surface topology. In contrast to a Mott-Hubbard and Slater pictures, this spin-driven Lifshitz transition appears in systems with small electron-electron correlation and large hybridization. We show that this situation is realized in 5d distorted perovskites with an half-filled t2g bands such as NaOsO3, where the strong p − d hybridization reduces the local moment, and spin-orbit coupling causes a large renormalization of the electronic mobility. This weakens the role of electronic correlations and drives the system towards an itinerant magnetic regime which enables spin-fluctuations.PACS numbers: 71.30.+h, 75.47.Lx, 71.27.+a Metal-to-insulator transitions (MITs) are one of the most important phenomena in solid-state physics and their fundamental understanding represents an enduring challenge in solid state theory [1,2]. Different mechanisms have been invoked to explain the formation of an insulating regime. Classical examples are realized in 3d transition metal oxides (TMOs), where the nonconducting state is typically understood within the MottHubbard model as arising from the competition between strong electron-electron interaction (U ) and the electronic mobility, associated to the (non-interacting) bandwidth (W ) [3][4][5]. When moving to the more spatially extended 4d and 5d orbitals the W increases and the U is expected to become smaller, leading to the tendency towards metallicity as in the itinerant magnet SrRuO 3 [6]. In contrast to these expectations, recent theory and experiment have revealed that in 'heavy' 5d TMOs, the enhanced spin-orbit coupling (SOC) strength [7] can lead to the formation of a variety of novel types of quantum states including unexpected insulating regimes [8][9][10][11]. In the most representative example, Sr 2 IrO 4 , the concerted action of a strong SOC and a moderate U leads to the opening of a small spectral gap [11,12] denominated relativistic Mott gap. Other and more rare types of MITs have been recently proposed for magnetic relativistic osmium oxides based on the Slater mechanism [13][14][15][16], driven by antiferromagnetic (AFM) order, where the gap is opened by exchange interactions and not by electronic correlation, [17] or Lifshitz-like processes [18,19], involving a rigid change of the Fermi surface topology [20].In this work we show that in weakly correlated (small U ) itinerant magnets the combined effect of longitudinal and rotational spin-fluctuations can cause a continu- * cesare.franchini@univie.ac.at ous MIT with Lifshitz characteristics, fundamentally different from relativistic Mott or purely Slater insulating states. The necessary conditions for the onset of this type of spin-driven Lifshitz MIT are the coexistence of a small U , a small local moment and an high degree of orbital ...

show abstract

supporting

confidence: 80%

Lifshitz transition driven by spin fluctuations and spin-orbit renormalization inNaOsO3

et al. 2016

View full text Add to dashboard Cite

show abstract

“…2). We observed the same peak (at the same resonant frequency) also on 1% Mg and 0.7% Si doped single crystals, but not on 5% and 10% Si doped samples, 12 where we did not find any sign of the SP transition also on the basis of magnetic susceptibility measurements.…”

supporting

confidence: 66%

Infrared signatures of the spin-Peierls transition inCuGeO3

et al. 1997

Self Cite

View full text Add to dashboard Cite

show abstract

“…37 Our results are similar to those obtained by other groups. 9,[38][39][40] The most striking feature is the strong temperature dependence of R() in the FIR spectral range, where the reflectivity changes from a metallic behavior at temperatures above 100 K by tending toward 100% for →0, to that of an insulator below 40 K. This can also easily be recognized on plots of the optical conductivity 1 (). As the temperature decreases, the low-frequency limit of 1 () drops continuously and, below 40 K, it is vanishing small, typical of insulators.…”

Section: Magnetic Susceptibilitymentioning

confidence: 99%

Low-temperature transport, thermodynamic, and optical properties of FeSi

Paschen¹,

Felder²,

et al. 1997

View full text Add to dashboard Cite

We present a comprehensive series of electrical transport ͑conductivity, magnetoresistance, and Hall effect͒, thermodynamic ͑specific heat, magnetic susceptibility, and magnetization͒, and optical ͑reflectivity͒ measurements in varying temperature ranges between 0.05 and 330 K on high-quality FeSi single crystals grown by vapor transport. The entire set of data can consistently be described with the usual relations for a ͑compensated n type͒ semiconductor if an unconventional band structure is assumed. Compared to the results of mean-field band-structure calculations, the height of the peaks in the total density of states around the energy gap is considerably enhanced, implying enhanced effective masses. Most likely correlation effects are the source of these features. At very low temperatures we encounter metallic behavior. A low concentration of correlated itinerant charge carriers coexists with interacting magnetic moments. ͓S0163-1829͑97͒05043-1͔

show abstract

Optical phonons in the reflectivity spectrum of FeSi

Cited by 13 publications

References 9 publications

Lifshitz transition driven by spin fluctuations and spin-orbit renormalization inNaOsO3

Lifshitz transition driven by spin fluctuations and spin-orbit renormalization inNaOsO3

Infrared signatures of the spin-Peierls transition inCuGeO3

Low-temperature transport, thermodynamic, and optical properties of FeSi

Contact Info

Product

Resources

About