Ambient-condition Raman spectra were collected in the strongly correlated NiS 1-xSe x pyrite (0≤x≤1.2). Two samples (x=0 and x=0.55) were studied as a function of pressure up to 10 GPa, and for the x=0.55 sample the pressure dependence of the infrared reflectivity was also measured (0-10 GPa). This gave a complete picture of the optical response of that system on approaching the metallic state both by application of pres-sure and/or by Se alloying, which corresponds to a volume expansion. A peculiar nonmonotonic (V-shaped) volume dependence was found for the quasiparticle spectral weight of both pure and Se-doped compounds. In the x=0.55 sample the vibrational frequencies of the chalcogen dimer show an anomalous volume dependence on entering the metallic phase. The abrupt softening observed, particularly significant for the Se-Se pair, indicates the relevant role of the softness of the Se-Se bond as previously suggested by theoretical calculations. © 2011 American Physical Society.

Combined Raman and infrared investigation of the insulator-to-metal transition in NiS(2−x)Se(x) compounds / C., Marini; A., Perucchi; D., Chermisi; Dore, Paolo; M., Valentini; D., Topwal; D. D., Sarma; Lupi, Stefano; Postorino, Paolo. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - STAMPA. - 84:23(2011), pp. 235134-1-235134-6. [10.1103/physrevb.84.235134]

Combined Raman and infrared investigation of the insulator-to-metal transition in NiS(2−x)Se(x) compounds

DORE, Paolo;LUPI, Stefano;POSTORINO, Paolo
2011

Abstract

Ambient-condition Raman spectra were collected in the strongly correlated NiS 1-xSe x pyrite (0≤x≤1.2). Two samples (x=0 and x=0.55) were studied as a function of pressure up to 10 GPa, and for the x=0.55 sample the pressure dependence of the infrared reflectivity was also measured (0-10 GPa). This gave a complete picture of the optical response of that system on approaching the metallic state both by application of pres-sure and/or by Se alloying, which corresponds to a volume expansion. A peculiar nonmonotonic (V-shaped) volume dependence was found for the quasiparticle spectral weight of both pure and Se-doped compounds. In the x=0.55 sample the vibrational frequencies of the chalcogen dimer show an anomalous volume dependence on entering the metallic phase. The abrupt softening observed, particularly significant for the Se-Se pair, indicates the relevant role of the softness of the Se-Se bond as previously suggested by theoretical calculations. © 2011 American Physical Society.
2011
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Combined Raman and infrared investigation of the insulator-to-metal transition in NiS(2−x)Se(x) compounds / C., Marini; A., Perucchi; D., Chermisi; Dore, Paolo; M., Valentini; D., Topwal; D. D., Sarma; Lupi, Stefano; Postorino, Paolo. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - STAMPA. - 84:23(2011), pp. 235134-1-235134-6. [10.1103/physrevb.84.235134]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/432916
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