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口頭

Volume collapse transition in TmTe; Competition between strong correlation and $$f$$-$$d$$ hybridization at high pressure

Jarrige, I.; Rueff, J.-P.*; Shieh, S.*; 田口 宗孝*; 大石 泰生*; 松村 隆*; 石井 啓文*; 平岡 望*; Cai, Y.*

no journal, , 

The pressure-induced mixed-valent state in TmTe is investigated up to 10.6 GPa using resonant inelastic X-ray scattering (RIXS) and the Anderson impurity model (AIM). The volume collapse transition (VCT) which takes place over the 2-4.3 GPa range is accompanied by a strong increase in the 4$$f$$-5$$d$$ hybridization. The valence in the collapsed state is found to be 2.5, showing that the VCT is inconsistent with the commonly accepted picture of Tm$$^{2+}$$ to Tm$$^{3+}$$ conversion. At 6 GPa, a transition in both magnetic and electronic ground states occurs at constant valence and hybridization. This could be indicative of a non-trivial instability of the 4$$f$$ ground state such as a non Fermi liquid behavior.

口頭

Volume collapse transition in TmTe; Competition between strong correlation and f-d hybridization at high pressure

Jarrige, I.; Rueff, J.-P.*; Shieh, S.*; Wang, J.*; 松村 隆*; 石井 啓文*; 平岡 望*; Cai, Y.*

no journal, , 

The pressure-induced mixed-valent state in TmTe is investigated up to 10.6 GPa using resonant inelastic X-ray scattering (RIXS) and the Anderson impurity model (AIM). The volume collapse transition (VCT) which takes place over the 2$$sim$$4.3 GPa range is accompanied by a strong increase in the 4f-5d hybridization. The valence in the collapsed state is found to be $$sim$$2.5, showing that the VCT is inconsistent with the commonly accepted picture of Tm$$^{2+}$$ to Tm$$^{3+}$$ conversion. At 6 GPa, a transition in both magnetic and electronic ground states occurs at constant valence and hybridization. This could be indicative of a non-trivial instability of the 4f ground state such as a non Fermi liquid behavior.

口頭

LaMnO$$_{3}$$における圧力下金属絶縁体転移のX線発光と吸収分光法の測定

Jarrige, I.; Shieh, S.*; 石井 啓文*; 平岡 望*; Cai, Y.*

no journal, , 

Here we report on a spectroscopic investigation of the intricate interplays between electronic, magnetic and structural properties of LaMnO$$_{3}$$ across its pressure-induced insulator to metal transition (IMT) at 32 GPa. We measure the Mn K-beta fluorescence line by X-ray emission spectroscopy (XES) and the Mn K-egde by X-ray absorption spectroscopy in the partial fluorescence yield mode (PFY-XAS). The XES spectra disclose a high-spin to low-spin transition accompanying the IMT that points to strongly interwoven charge and spin degrees of freedom, which is reminiscent of the Mott perspective. On the other hand, close insight is gained on the structure from the Mn K pre-edge region, where evidence is found for a complete suppression of the Jahn-Teller distortions at the IMT. This is congruent with the scenario that the gap closure results from the progressive pressure-induced degeneracy of the majority-spin eg band, thus suggesting that the IMT in LaMnO$$_{3}$$ is not a plain Mott transition.

口頭

Competition between multi-channel Kondo effect and f delocalization in TmTe at high pressure

Jarrige, I.; Rueff, J.-P.*; Shieh, S.*; 田口 宗孝*; 石井 啓文*; Cai, Y. Q.*

no journal, , 

Identifying the mechanism of Kondo phenomena is arguably one of the most exciting and widely studied issues in condensed matter physics. Intermediate-valent Tm compounds stand out as potential candidates for multichannel Kondo (ncK) effect, since both integer valences Tm$$^{2+}$$ and Tm$$^{3+}$$ are magnetic. Using resonant inelastic X-ray scattering and the Anderson impurity model, we probed the Tm valence and 4f-5d hybridization in the high-pressure intermediate-valent TmTe compound. Our results reveal that the f delocalization is discontinuous, characterized by a previously unobserved plateau-like behavior over the 4.3$$sim$$6.5 GPa range. This is at odds with the usual, continuous Kondo-like f delocalization, and is interpreted as an experimental observation of the effect of culminating ncK scattering of d electrons from local moments on the electronic structure.

口頭

Competition between multi-channel Kondo effect and f delocalization in TmTe at high pressure

Jarrige, I.; Rueff, J.-P.*; Cai, Y. Q.*; Shieh, S.*; 石井 啓文*; 田口 宗孝*

no journal, , 

Among numerous f electron systems which present Kondo properties, intermediate-valent Tm compounds stand out as potential candidates for multichannel Kondo (ncK) effect, since both integer valences Tm2+ and Tm3+ are magnetic. Using resonant inelastic X-ray scattering and the Anderson impurity model, we probed the Tm valence and 4f-5d hybridization in the high-pressure intermediate-valent TmTe compound. Our results reveal that the f delocalization is discontinuous, characterized by a previously unobserved plateau-like behavior between the volume collapse transition and the structural transition (4.3$$sim$$6.5 GPa), with an associated valence (2.55) at odds with the near-trivalency previously reported. This is at odds with the usual, continuous Kondo-like f delocalization, and is interpreted as an experimental observation of the effect of culminating ncK scattering of d electrons from local moments on the electronic structure.

口頭

Single-channel vs multi-channel Kondo effects; SmTe and TmTe studied via resonant inelastic X-ray scattering under high pressure

Jarrige, I.; Rueff, J.-P.*; Shieh, S.*; 田口 宗孝*; 大石 泰生*; 松村 武*; 石井 啓文*; 平岡 望*; Cai, Y. Q.*

no journal, , 

Using resonant inelastic X-ray scattering and the Anderson impurity model, we estimated the pressure dependence of the Sm and Tm valence and 4 f -5d hybridization in the respectively single and multi-channel Kondo compounds SmTe and TmTe. We observed a usual, continuous Kondo-like f delocalization for SmTe as a function of pressure. On the contrary, our results reveal that the f delocalization in TmTe is discontinuous, characterized by a previously unobserved plateau-like behavior between 4.3 and 6.5 GPa. This is interpreted as an experimental observation of the effect of culminating multi-channel Kondo scattering of d electrons from local moments on the electronic structure. Our study raises the interesting possibility that an NCK effect realized in a compressed mixed-valent f system could impede the concomitant electron delocalization.

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