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Electronic structure of the thermoelectric charge density wave material CeTe2-xSbx investigated via angle-resolved photoemission spectroscopy

Tue, 30 Jun 2026 15:00:00 GMT

Title: Electronic structure of the thermoelectric charge density wave material CeTe2-xSbx investigated via angle-resolved photoemission spectroscopy Author(s): Seong, Seungho; Han, Sang Wook; Min, B. I.; Kwon, Yong Seung; Kang, J. -S Abstract: Employing angle-resolved photoemission spectroscopy (ARPES), we have investigated the electronic structures of Sb-substituted CeTe2, CeTe2-xSbx(0 <= x <= 0.5), which exhibit charge density wave (CDW) transitions and enhanced thermoelectric (TE) properties and are also predicted to be topological material candidates. Two flat Ce 4 f states are observed, one at approximately-3.5 eV and the other at approximately-0.8 eV, which represent the 4 f (1)-> 4 f(0 )transition and the Kondo-like 4 f(1) L-0 -> 4 f(1) L(1 )transition (where L & strns; is a ligand hole) of trivalent Ce3+ ions, respectively. Two diamond-shaped inner and outer Fermi surfaces (FSs) are observed, which arise from the holelike band centered at P and from the folding of the two-dimensional Brillouin zone (BZ) into the three-dimensional (3D) BZ, respectively. The measured outer FSs demonstrate the non-negligible effect of the 3D electronic structures of CeTe2-xSbx. The CDW-induced zigzag features are observed in the FS of x = 0, but are not observed in the FSs of x > 0, indicating the rapid suppression of the CDW state by the Sb substitution. This finding suggests that the increased resistivity at x > 0, despite the weakened CDW formation, is possibly due to the disorder-induced localization by the Sb substitution, leading to the optimal TE properties at a specific x. The measured band structures of CeTe(2-x)Sb(x)via ARPES exhibit very similar features for different x values, except for the shift of the whole bands toward the Fermi level (EF) with increasing x. This reflects the hole doping introduced by the Sb substitution, which is in good agreement with the calculated band structures. In the ARPES data of x > 0, crossing bands are observed near the X point at approximately-1 eV, which closely resemble Dirac points, suggesting the existence of topological electronic structures of CeTe2-xSbx. Linear dichroism ARPES measurements on CeTe1.75Sb0.25 show that the EF-crossing Te/Sb p states along X-P-X and M-P-M have both in-plane and out-of-plane character, while those along M-X-M have mainly in-plane character.

A comparative synthesis study of α-MnTe across solid-state, Arc-melting, and Te-flux routes

Fri, 31 Jul 2026 15:00:00 GMT

Title: A comparative synthesis study of α-MnTe across solid-state, Arc-melting, and Te-flux routes Author(s): Kim, Bomin; Jeong, Yunseong; Baek, Wonjung; Kim, Hobyeong; Rhee, Taeseong; Cho, Beopgil; Choi, Woo-Jae; Ha, Jae-Hyun; Park, Jaemun; Hong, Jung-Il; Kwon, Yong Seung; Seo, Jungpil; Park, Keeseong Abstract: Although alpha-MnTe has attracted renewed interest in both thermoelectric and altermagnetic contexts, direct comparisons of practically accessible synthesis routes within a common experimental framework remain limited. Here, we compare conventional solid-state reaction, arc melting and Te self-flux growth methods under a common framework of composition control and thermal history. Within the explored conditions, the phase outcome depends not only on the nominal starting composition but also on route-dependent synthesis environments, including volatilization in sealed ampoules, repeated remelting and rapid quenching in arc melting, and crystal-flux interfacial segregation in Te self-flux growth. In the solid-state route, slow heating with a slightly Mn-rich starting composition was associated with reduced MnTe2 and alpha-MnTe-dominant products. Arc melting yielded alpha-MnTe-dominant products without post-annealing, accompanied by dendritic-like microstructures. Te self-flux growth yielded single crystals, although a minor MnTe2-rich interfacial or surface layer often remained. While the present dataset does not define a rigorous phase boundary or a definitive mechanistic model, it provides a systematic comparative framework for route-dependent phase outcomes and impurity persistence in alpha-MnTe synthesis.

A comparative synthesis study of α-MnTe across solid-state, Arc-melting, and Te-flux routes

Fri, 31 Jul 2026 15:00:00 GMT

Polaronic Quasiparticles in the Valence-Transition Compound TmSe_{1-x}Te_{x}

Tue, 30 Sep 2025 15:00:00 GMT

Title: Polaronic Quasiparticles in the Valence-Transition Compound TmSe_{1-x}Te_{x} Author(s): Min, Chul-Hee; Müller, Simon; Choi, Woojae; Dudy, Lenart; Zabolotnyy, Volodymyr B.; Heber, Michael; Denlinger, Jonathan D.; Kang, Chang-jong; Kalläne, Matthias; Wind, Nils O.; Scholz, Markus R.; Lee, Tienlin; Schlueter, Christoph; Gloskovskii, Andrei V.; Rienks, Emile D.L.; Hinkov, Vladimir; Bentmann, Hendrik; Kwon, Yong Seung; Reinert, Friedrich T.; Kim, H. D.; Rossnagel, Kai Abstract: Exotic quasiparticle states have been proposed in mixed-valent compounds exhibiting valence transitions. However, clear spectroscopic evidence identifying these states has remained elusive. Using synchrotron-based hard x-ray and extreme ultraviolet photoemission spectroscopy, we have probed the Tm 3d and 4f emissions in TmSe_{1-x}Te_{x}, where a Te concentration-dependent semimetal-insulator transition occurs alongside the valence transition. Our photoemission results, which are characteristic of the bulk, track this combined transition across the critical concentration (x_{c}=0.29). Notably, our results reveal a noninteger valence for the insulating phase and a novel quasiparticle excitation in the semimetallic phase: a Holstein polaron that extends beyond the standard periodic Anderson model.