Pressure Tuning of an Ionic Insulator into a Heavy Electron Metal: An Infrared Study of YbS

Matsunami, Masaharu; Okamura, Hidekazu; Ochiai, Akira; Nanba, Tetsuya

doi:10.1103/physrevlett.103.237202

Cited by 28 publications

(40 citation statements)

References 18 publications

(53 reference statements)

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“…3 The usual Kramers-Kronig (KK) transform 28,29 was applied to the R 0 (ω) to obtain the complex refractive indexn(ω).n(ω) was then used to derive the reflectance spectrum, R d (ω), that was expected in a DAC, taking into account the refractive index of diamond (2.4) as previously discussed. 16,17,19,20 The R d (ω) data at P =0 in Fig. 1(a) are the results of this analysis.…”

Section: Resultsmentioning

confidence: 90%

“…More details of the high pressure IR experiments can be found elsewhere. 16,17,20 The R(ω) measurement without using a DAC was previously described. [25][26][27] …”

Section: Methodsmentioning

confidence: 99%

“…[16][17][18][19][20] A pair of diamond anvils with 0.6 mm culet diameter and a metal gasket (stainless steel 301) were used to seal the sample, pressure transmitting medium, and small ruby pieces used to monitor the pressure via its fluorescence. 17 A flat, as-grown surface of a single crystal sample 2 was closely attached on the culet surface of the anvil, which was of type IIa with low density of impurities.…”

Section: Methodsmentioning

confidence: 99%

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Pressure suppression of unconventional charge-density-wave state in PrRu4P12studied by optical conductivity

et al. 2012

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Optical conductivity [σ(ω)] of PrRu4P12 has been studied under high pressure to 14 GPa, at low temperatures to 8 K, and at photon energies 12 meV-1.1 eV. The energy gap in σ(ω) at ambient pressure, caused by a metal-insulator transition due to an unconventional charge-density-wave formation at 63 K, is gradually filled in with increasing pressure to 10 GPa. At 14 GPa and below 30 K, σ(ω) exhibits a pronounced Drude-type component due to free carriers. This indicates that the initial insulating ground state at zero pressure has been turned into a metallic one at 14 GPa. This is consistent with a previous resistivity study under pressure, where the resistivity rapidly decreased with cooling below 30 K at 14 GPa. The evolution of electronic structure with pressure is discussed in terms of the hybridization between the 4f and conduction electrons.

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Section: Resultsmentioning

confidence: 90%

“…More details of the high pressure IR experiments can be found elsewhere. 16,17,20 The R(ω) measurement without using a DAC was previously described. [25][26][27] …”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Pressure suppression of unconventional charge-density-wave state in PrRu4P12studied by optical conductivity

et al. 2012

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“…Due to the large refractive index of diamond (2.4), therefore, R d (ω) may significantly differ from R 0 (ω), 35 as actually observed for a few compoudns. [36][37][38] Hence a careful analysis is required for the data measured with DAC, as discussed later. Figure 2 summarizes the reflectance data of Sr122 measured at P =0, 2.5, 4, and 6 GPa.…”

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confidence: 99%

Pressure Suppression of Spin-Density-Wave Gap in the Optical Conductivity of SrFe₂As₂

et al. 2013

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Optical reflectance R(ω) of a pressure-induced superconductor SrFe2As2 has been measured under external pressure to 6 GPa and at temperatures to 8 K. Optical conductivity σ(ω) has been derived from the measured R(ω). At ambient pressure, in the antiferromagnetic state below TN=198 K, a pronounced feature develops in σ(ω) due to the opening of a spin density wave (SDW) gap, as already reported in the literature. With increasing pressure, the SDW gap feature in σ(ω) is progressively suppressed. At 4 GPa, where the sample is superconducting, the SDW gap feature in σ(ω) is strongly reduced than that at ambient pressure, but is still clearly observed. At 6 GPa, the SDW gap is completely suppressed. The pressure evolutions of the SDW gap magnitude and the spectral weight closely follow the pressure evolution of TN. PACS numbers:Regarding the superconductivity (SC) exhibited by Fe-based compounds, 1 the pressure-induced SC exhibited by the stoichiometric "122" compounds AFe 2 As 2 (A=Ba, Ca, Sr, Eu) have attracted much interest. 2-13 They exhibit SC with external pressure only, although many other families of Fe based superconductors require some form of chemical doping or deviation from stoichiometry to exhibit SC. 1 In particular, SrFe 2 As 2 (Sr122) and BaFe 2 As 2 (Ba122) show pressure-induced SC at relatively high temperatures of T c =34 K 5,7-9 and 28 K, 4,7,9,11 , respectively. Interestingly, the 122 compounds also show SC with chemical doping, as shown by (Sr, K)Fe 2 As 2 , 14 Sr(Fe,Co) 2 As 2 , 15 and SrFe 2 (As, P) 2 . 16 At ambient pressure, the stoichiometric 122 compounds are antiferromagnetic (AFM), poor metals. For Sr122 and Ba122, the AFM transition temperature (T N ) is 198 K and 136 K, respectively. At T N , the resistivity [ρ(T )] shows a kink and rapid decrease with cooling below T N . With increasing pressure, T N is gradually lowered, and the kink in ρ(T ) becomes broadened. Above a critical pressure, the SC appears. Similar suppression of AFM and emergence of SC have also been observed with chemical doping. [14][15][16] In this regard, both methods have provided a lot of insight, but one advantage of the pressure technique compared with chemical doping is that the former does not cause disorder in the crystal lattice.However, there is an additional complication regarding the pressure-induced SC in the 122 compounds. Namely, it has been shown that the pressure evolutions of the AFM and SC states strongly depend on the hydrostaticity. 8,11,12 Here, hydrostaticity refers to how isotropic the pressure acting on the sample is. The hydrostaticity in a high pressure experiment depends on the types of pressure cell and pressure transmitting medium used. Figure 1 summarizes the results of high pressure studies on Sr122. 4,5,7-9 As discussed in detail later, these results show that the AFM state is suppressed and SC appears at lower pressure when the applied pressure is less hydrostatic (more uniaxial). This may indicate that a uniaxial stress promotes SC in the 122 compounds.To probe the microscopic elect...

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“…Matsunami et al extended the high-pressure IR study of YbS down to 20 meV using IR-SR. 116) Figure 12 8 GPa, but then shows a marked increase with pressure. Namely, R d ð!Þ spectrum below 0.1 eV shows a rapid increase with pressure, reaching about 0.9 above 10 GPa, and the phonon peak disappears quickly with increasing pressure.…”

Section: Rare-earth (''Heavy-fermion'') Compoundsmentioning

confidence: 99%

Infrared and Terahertz Spectroscopy of Strongly Correlated Electron Systems under Extreme Conditions

Kimura

Okamura

2013

J. Phys. Soc. Jpn.

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Owing to its high brilliance, infrared and terahertz synchrotron radiation (IR/THz-SR) has emerged as a powerful tool for spectroscopy under extreme (i.e., technically more difficult) experimental conditions such as high pressure, high magnetic field, high spatial resolution, and a combination of these. The methodologies for pressure-and magneticfield-dependent spectroscopy and microscopy using IR/THz-SR have advanced rapidly worldwide. By applying them to strongly correlated electron systems (SCESs), many experimental studies have been performed on their electronic structures and phonon/molecular vibration modes under extreme conditions. Here, we review the recent progress of methodologies of IR/THz-SR spectroscopy and microscopy, and the experimental results on SCESs and other systems obtained under extreme conditions.

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Pressure Tuning of an Ionic Insulator into a Heavy Electron Metal: An Infrared Study of YbS

Cited by 28 publications

References 18 publications

Pressure suppression of unconventional charge-density-wave state in PrRu4P12studied by optical conductivity

Pressure suppression of unconventional charge-density-wave state in PrRu4P12studied by optical conductivity

Pressure Suppression of Spin-Density-Wave Gap in the Optical Conductivity of SrFe₂As₂

Infrared and Terahertz Spectroscopy of Strongly Correlated Electron Systems under Extreme Conditions

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Pressure Tuning of an Ionic Insulator into a Heavy Electron Metal: An Infrared Study of YbS

Cited by 28 publications

References 18 publications

Pressure suppression of unconventional charge-density-wave state in PrRu4P12studied by optical conductivity

Pressure suppression of unconventional charge-density-wave state in PrRu4P12studied by optical conductivity

Pressure Suppression of Spin-Density-Wave Gap in the Optical Conductivity of SrFe2As2

Infrared and Terahertz Spectroscopy of Strongly Correlated Electron Systems under Extreme Conditions

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Pressure Suppression of Spin-Density-Wave Gap in the Optical Conductivity of SrFe₂As₂