Characterization of 1T-TiSe2 surface by means of STM and XPD experiments and model calculations

NbS3: A unique quasi-one-dimensional conductor with three charge density wave transitions

“…It has been reported previously that NbS 3 is susceptible to S loss with heating [43]. It is therefore likely that the variation in specific conductivity found in the NbS 3 -II samples is a result of S vacancies acting as donors, similar to the observed behavior of TiS 3 [44,45] and TiSe 2 [46,47]. Consequently, the higher concentration of S vacancies would account for the reduced electrical resistivity observed in samples, belonging to the low-ohmic sub-phase.…”

Suppression of the Charge Density Wave State in Two‐Dimensional 1T‐TiSe2 by Atmospheric Oxidation

“…[1] In the last two years,t wodimensional (2D) TiSe 2 ,N bSe 2 ,a nd TaS 2 have attracted intensive interest in condensed-state physics for exploring their complex many-body electronic ground states at low dimensions. [7] We first carried out variable-temperature electrical measurement, which is astandard method to study the CDWb ehavior of TiSe 2 bulk crystals, [6] on mechanically exfoliated TiSe 2 flakes to verify the existence of the CDWstate in these thin flakes.T he fourprobe resistivity-temperature (1-T)c urve measured on [2a] However,e xperimental studies on these metallic 2D TMDCs are still very limited, compared with semiconducting 2D TMDCs,such as MoS 2 and WSe 2 ,m ainly due to the challenges of preserving their pristine properties as these metallic thin flakes undergo rapid oxidations upon exposure to air.…”

“…Based on the understanding of the oxidation mechanism, we utilized as urface capping layer of atomic layer deposition (ALD)-derived Al 2 O 3 to effectively maintain the intrinsic properties of 2D TiSe 2 .O ur results show that the chemical stability of 2D TMDCs significantly affects their phasetransition properties and the oxidation mechanism of these 2D materials is different from other materials owing to their unique structure and chemical compositions.Single-crystalline 1T-TiSe 2 is al ayered van der Waals material with ah exagonal crystal structure (a = b = 3.538 and c = 6.008 ,F igure 1a), showing as econd-order phase transition to aC DW state at at emperature (T CDW )o fa bout 200 K. [6] Thea tomically resolved scanning tunneling microscopy (STM) image of the surface of 1T-TiSe 2 reveals that the interatomic spacing a is expanded by about 0.3 relative to the bulk value (Figure 1a), which may be attributed to relaxation effects at the surface. [7] We first carried out variable-temperature electrical measurement, which is astandard method to study the CDWb ehavior of TiSe 2 bulk crystals, [6] on mechanically exfoliated TiSe 2 flakes to verify the existence of the CDWstate in these thin flakes.T he fourprobe resistivity-temperature (1-T)c urve measured on…”

“…Single-crystalline 1T-TiSe 2 is al ayered van der Waals material with ah exagonal crystal structure (a = b = 3.538 and c = 6.008 ,F igure 1a), showing as econd-order phase transition to aC DW state at at emperature (T CDW )o fa bout 200 K. [6] Thea tomically resolved scanning tunneling microscopy (STM) image of the surface of 1T-TiSe 2 reveals that the interatomic spacing a is expanded by about 0.3 relative to the bulk value ( Figure 1a), which may be attributed to relaxation effects at the surface. [7] We first carried out variable-temperature electrical measurement, which is astandard method to study the CDWb ehavior of TiSe 2 bulk crystals, [6] on mechanically exfoliated TiSe 2 flakes to verify the existence of the CDWstate in these thin flakes.T he fourprobe resistivity-temperature (1-T)c urve measured on atypical TiSe 2 flake device (ca. 9nmthick, Figure 1b)shows ac learly similar shape to that of bulk crystals (Supporting Information, Figure S1c), and the phase-transition temperature of this flake is determined to be about 192 Kbytaking the local minimum of the derivative of the curve (Figure 1b, red line).…”

Molecular Beam Epitaxy and High-Pressure Studies of van der Waals Magnets

“…A for MoSe 2 , 6.48Å for WSe 2 [235,236,237,238,239]. In addition to the emergence of new XRD peaks in the thicker MnSe x films, an enhancement in the magnetization is also observed.…”