High-quality large 1T phase of TiX_(2)(X = Te, Se, and S) single crystals have been grown by chemical vapor transport using iodine as a transport agent. The samples are characterized by compositional and structural an...High-quality large 1T phase of TiX_(2)(X = Te, Se, and S) single crystals have been grown by chemical vapor transport using iodine as a transport agent. The samples are characterized by compositional and structural analyses, and their properties are investigated by Raman spectroscopy. Several phonon modes have been observed, including the widely reported A_(1g) and E_(8) modes, the rarely reported E_(u) mode(-83 cm^(-1) for TiTe_(2), and -185 cm^(-1)for TiS_(2)), and even the unexpected K mode(-85 cm^(-1)) of TiTe_(2). Most phonons harden with the decrease of temperature, except that the K mode of TiTe_(2) and the E_(u) and “A_(2u)/Sh” modes of TiS_(2) soften with the decrease of temperature. In addition, we also found phonon changes in TiSe_(2) that may be related to charge density wave phase transition. Our results on TiX_(2) phonons will help to understand their charge density wave and superconductivity.展开更多
We systemically investigate the nature of Ce 4f electrons in structurally layered heavy-fermion compounds Ce_(m)M_(n)In_(3m+2n)(with M=Co,Rh,Ir,and Pt,m=1,2,n=0–2),at low temperature using on-resonance angle-resolved...We systemically investigate the nature of Ce 4f electrons in structurally layered heavy-fermion compounds Ce_(m)M_(n)In_(3m+2n)(with M=Co,Rh,Ir,and Pt,m=1,2,n=0–2),at low temperature using on-resonance angle-resolved photoemission spectroscopy.Three heavy quasiparticle bands f^(0),f^(1/7/2)and f^(1/5/2),are observed in all compounds,whereas their intensities and energy locations vary greatly with materials.The strong f0 states imply that the localized electron behavior dominates the Ce 4f states.The Ce 4f electrons are partially hybridized with the conduction electrons,making them have the dual nature of localization and itinerancy.Our quantitative comparison reveals that the f^(1/5/2)–f^(0)intensity ratio is more suitable to reflect the 4f-state hybridization strength.展开更多
对宏观量子性质进行精确调控是量子材料实现工业应用的关键.利用超短脉冲激光共振激发量子材料内部某种集体模式,宏观上产生亚稳态是目前凝聚态物理学中一个正在蓬勃发展的领域,如光致超导[1]、光增强超导以及电荷密度波序[2]、光致铁电...对宏观量子性质进行精确调控是量子材料实现工业应用的关键.利用超短脉冲激光共振激发量子材料内部某种集体模式,宏观上产生亚稳态是目前凝聚态物理学中一个正在蓬勃发展的领域,如光致超导[1]、光增强超导以及电荷密度波序[2]、光致铁电性[3],以及光致二维电子态[4]等.过渡金属硫族化合物1T-TiSe2作为一种典型的电荷密度波(charge density wave,CDW)材料存在许多新的量子相.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12074436 and U1930116)the Innovation-driven Plan in Central South University (Grant No. 2016CXS032)。
文摘High-quality large 1T phase of TiX_(2)(X = Te, Se, and S) single crystals have been grown by chemical vapor transport using iodine as a transport agent. The samples are characterized by compositional and structural analyses, and their properties are investigated by Raman spectroscopy. Several phonon modes have been observed, including the widely reported A_(1g) and E_(8) modes, the rarely reported E_(u) mode(-83 cm^(-1) for TiTe_(2), and -185 cm^(-1)for TiS_(2)), and even the unexpected K mode(-85 cm^(-1)) of TiTe_(2). Most phonons harden with the decrease of temperature, except that the K mode of TiTe_(2) and the E_(u) and “A_(2u)/Sh” modes of TiS_(2) soften with the decrease of temperature. In addition, we also found phonon changes in TiSe_(2) that may be related to charge density wave phase transition. Our results on TiX_(2) phonons will help to understand their charge density wave and superconductivity.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 12074436 and 11574402)the Innovation-Driven Plan in Central South University (Grant No. 2016CXS032)+7 种基金support through the Swedish Research Council (VR) and the Swedish National Infrastructure for Computing (SNIC),for computing time on computer cluster Triolith at the NSC center Link?ping (supported by VR Grant No. 2018-05973)the support from the Swedish Research Council (VR) through a Starting Grant (No. Dnr. 2017-05078)support from the Swedish Research Council(VR)the Knut and Alice Wallenberg foundationsupported by a Marie Sklodowska-Curie Action,International Career Grant through the European Commission and Swedish Research Council (VR)(Grant No. INCA-2014-6426)a VR neutron project (Grant No. BIFROST, Dnr. 2016-06955)granted by the Carl Tryggers Foundation for Scientific Research (Grant Nos. CTS-16:324 and CTS-17:325)the auspices of the U.S. Department of Energy,Office of Basic Energy Sciences,Division of Materials Sciences and Engineering
文摘We systemically investigate the nature of Ce 4f electrons in structurally layered heavy-fermion compounds Ce_(m)M_(n)In_(3m+2n)(with M=Co,Rh,Ir,and Pt,m=1,2,n=0–2),at low temperature using on-resonance angle-resolved photoemission spectroscopy.Three heavy quasiparticle bands f^(0),f^(1/7/2)and f^(1/5/2),are observed in all compounds,whereas their intensities and energy locations vary greatly with materials.The strong f0 states imply that the localized electron behavior dominates the Ce 4f states.The Ce 4f electrons are partially hybridized with the conduction electrons,making them have the dual nature of localization and itinerancy.Our quantitative comparison reveals that the f^(1/5/2)–f^(0)intensity ratio is more suitable to reflect the 4f-state hybridization strength.
文摘对宏观量子性质进行精确调控是量子材料实现工业应用的关键.利用超短脉冲激光共振激发量子材料内部某种集体模式,宏观上产生亚稳态是目前凝聚态物理学中一个正在蓬勃发展的领域,如光致超导[1]、光增强超导以及电荷密度波序[2]、光致铁电性[3],以及光致二维电子态[4]等.过渡金属硫族化合物1T-TiSe2作为一种典型的电荷密度波(charge density wave,CDW)材料存在许多新的量子相.
