“…As shown in Figure 3, it shows two discontinuities at 202 and 222 K, and a smooth slope change at about 150 K, similar to that observed in 2 H -NbSe 2 (Leblanc and Nader 2010) at approximately the same temperature. An unusual aspect in β ( T ) is that it decreases when the temperature is raised and at 222 K it jumps to a value the same as at 90 K. The amplitude of this jump is about 92% of the whole variations of β ( T ) on our temperature range.Figure 3
Resistivity anisotropy of (SmS)
1.25
TiS
2
.…”
BackgroundThe misfit layer compound (SmS)1.25 TiS2 has a layered structure which consists on an alternating sequence of one |SmS| bi-layer adopting a NaCl distorted structure and one |TiS2| tri-layer with the Ti atoms plane sandwiched by two sulfur ones and the Ti atoms octahedrally coordinated. Stacking is along the c-axis. Each of these two subsystems has its own 3D lattice and space group, and they have a common (b*, c*) plane in the reciprocal lattice so that the a axes are parallel and of irrational ratio. The physical properties of this compound have never been investigated. Accurate resistivity anisotropy measurement down to the liquid nitrogen temperature is presented here.FindingsThe in-plane resistivity shows an anomaly at 202 K, and the out-of-plane resistivity shows also anomalies at 202 and 222 K and an upward curvature between 100 and 222 K. Consequently, the resistivity anisotropy shows peculiarities; mainly an important jump at 222 K.This behavior is discussed in the framework of a possible magnetic ordering and/or anisotropic lattices distortions. Although, the role of this work is to draw the attention to these features and further investigations to confirm these results would be of interest.ConclusionFurther investigations are needed, mainly magnetic and crystallographic in function of temperature in order to conclude definitely whether there is any phase transition or not.
“…As shown in Figure 3, it shows two discontinuities at 202 and 222 K, and a smooth slope change at about 150 K, similar to that observed in 2 H -NbSe 2 (Leblanc and Nader 2010) at approximately the same temperature. An unusual aspect in β ( T ) is that it decreases when the temperature is raised and at 222 K it jumps to a value the same as at 90 K. The amplitude of this jump is about 92% of the whole variations of β ( T ) on our temperature range.Figure 3
Resistivity anisotropy of (SmS)
1.25
TiS
2
.…”
BackgroundThe misfit layer compound (SmS)1.25 TiS2 has a layered structure which consists on an alternating sequence of one |SmS| bi-layer adopting a NaCl distorted structure and one |TiS2| tri-layer with the Ti atoms plane sandwiched by two sulfur ones and the Ti atoms octahedrally coordinated. Stacking is along the c-axis. Each of these two subsystems has its own 3D lattice and space group, and they have a common (b*, c*) plane in the reciprocal lattice so that the a axes are parallel and of irrational ratio. The physical properties of this compound have never been investigated. Accurate resistivity anisotropy measurement down to the liquid nitrogen temperature is presented here.FindingsThe in-plane resistivity shows an anomaly at 202 K, and the out-of-plane resistivity shows also anomalies at 202 and 222 K and an upward curvature between 100 and 222 K. Consequently, the resistivity anisotropy shows peculiarities; mainly an important jump at 222 K.This behavior is discussed in the framework of a possible magnetic ordering and/or anisotropic lattices distortions. Although, the role of this work is to draw the attention to these features and further investigations to confirm these results would be of interest.ConclusionFurther investigations are needed, mainly magnetic and crystallographic in function of temperature in order to conclude definitely whether there is any phase transition or not.
“…The anisotropic parameters are about γ H c2 = 1.55 from the upper critical magnetic fields and coherence length which is little bit smaller than those of crystalline Cu-intercalated TiSe 2 (γ H c2 = 1.7 in Cu 0.07 TiSe 2 ) compound [29,30]. Even though the anisotropy value is smaller than those of single-crystalline 2H-TX 2 [16], this anisotropy value 1.55 is thought to be significant for polycrystalline-sintered material. Figure 4 depicts the specific heat C p divided by temperature T , C p /T , as a function of T 2 of (SnSe) 1.18 (TiSe 2 ) 2 under static magnetic fields of H = 0 T and H = 5 T. Because it is a normal state with H = 5 T, the C p under high magnetic fields contain only lattice and electronic contributions without superconductivity.…”
We report the superconducting properties in the misfit layered compound (SnSe)1.18 (TiSe2)2 with critical temperature Tc=3.3 K at ambient pressure. Even though this compound is a polycrystalline compound, it shows anisotropic properties from the X‐ray diffraction, electrical transport, magnetization, and high‐resolution transmission electron microscopy measurements. The anisotropic parameter γHc2 of the compound is about 1.55 which is obtained from the superconducting parameters of the zero‐temperature‐limit upper critical field Hc2false(0false) and coherence length ξ using the Werthamer–Helfand–Hohenberg (WHH) formula. The small values of specific heat jump ΔC/γTc and electron–phonon coupling constant λnormale−italicph indicate a weak‐coupling BCS superconductor. The critical current density is exceptionally high (8000 A cm−2) compared to other misfit‐layer superconductors.
Isothermal hysteresis of magnetization, and critical current density (inset), with respect to the applied magnetic field for various temperatures.
“…15 However, resistivity measurements show an anisotropy of nearly three orders of magnitude (700), which is clearly at odds with the far smaller anisotropy found in the critical field measurements. 32 Fermi surface measurements also point to strongly twodimensional bands, so that the out-of-plane coherence length ξ ⊥ should be probably far below the value from critical field measurements. 8,16 Regarding the in-plane coherence length ξ , it is striking that the values given are much larger than 094502-5 those reported in 2H -NbSe 2 , of 10 nm.…”
We report a characterization of surfaces of the dichalcogenide TaSe 2 using scanning tunneling microscopy and spectroscopy at 150 mK. When the top layer has the 2H structure and the layer immediately below the 1T structure, we find a singular spatial dependence of the tunneling conductance below 1 K, changing from a zero-bias peak on top of Se atoms to a gap in between Se atoms. The zero-bias peak is additionally modulated by the commensurate 3a 0 × 3a 0 charge-density wave of 2H -TaSe 2 . Multilayers of 2H -TaSe 2 show a spatially homogeneous superconducting gap with a critical temperature also of 1 K. We discuss possible origins for the peculiar tunneling conductance in single layers.
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