arXiv subjects

David B. Lioi

Publications and source records attributed to David B. Lioi.

3 recordsLinked to original sources

arXiv2025

In-plane anisotropy of charge density wave fluctuations in 1$T$-TiSe$_2$

We report measurements of anisotropic triple-$q$ charge density wave (CDW) fluctuations in the transition metal dichalcogenide 1$T$-TiSe$_2$ over a large volume of reciprocal space with X-ray diffuse scattering. Above the transition temperature, $T_{\text{CDW}}$, the out-of-plane diffuse scattering is characterized by rod-like structures which indicate that the CDW fluctuations in neighboring layers are largely decoupled. In addition, the in-plane diffuse scattering is marked by ellipses which reveal that the in-plane fluctuations are anisotropic. Our analysis of the diffuse scattering line shapes and orientations suggests that the three charge density wave components contain independent phase fluctuations. At $T_{\text{CDW}}$, long range coherence is established in both the in-plane and out-of-plane directions, consistent with the large observed value of the CDW gap compared to $T_{\text{CDW}}$, and the predicted presence of a hierarchy of energy scales.

cond-mat.str-el↗

arXiv2017

Observation of a Charge Density Wave Incommensuration Near the Superconducting Dome in CuxTiSe2

X-ray diffraction was employed to study the evolution of the charge density wave (CDW) in CuxTiSe2 as a function of copper intercalation in order to clarify the relationship between the CDW and superconductivity. The results show a CDW incommensuration arising at an intercalation value coincident with the onset of superconductivity at around x=0.055(5). Additionally, it was found that the charge density wave persists to higher intercalant concentrations than previously assumed, demonstrating that the CDW does not terminate inside the superconducting dome. A charge density wave peak was observed in samples up to x=0.091(6), the highest copper concentration examined in this study. The phase diagram established in this work suggests that charge density wave incommensuration may play a role in the formation of the superconducting state.

cond-mat.supr-con↗

arXiv2016

Photon-Induced Selenium Vacancies in TiSe2

TiSe2 is a member of transition metal dichalcogenide family of layered van-der-Waals materials that exhibits some distinctive electronic and optical properties. Here, we perform Raman spectroscopy studies on single crystal TiSe2 to investigate photon-induced defects associated with formation of selenium vacancies. Two additional Eg phonon peaks are observed in the laser-irradiated regions, consistent with Raman spectra of selenium deficient TiSe2. Temperature dependent studies of the threshold laser intensity necessary to form selenium vacancies show that there is a linear dependence. We extract the relevant activation energy for selenium vacancy nucleation. The impact of these results on the properties of strongly correlated electron states in TiSe2 are discussed.

cond-mat.str-el↗