Single Crystal Growth and Physical Property Characterization of Non-centrosymmetric Superconductor PbTaSe ₂

Abstract

We report on the single crystal growth and superconducting properties of PbTaSe2 with the non-centrosymmetric crystal structure. By using the chemical vapor transport technique, centimeter-size single crystals are successfully obtained. The measurement of temperature dependence of electrical resistivity 𝜌(𝑇 ) in both normal and superconducting states indicates a quasi-two-dimensional electronic state in contrast to that of polycrystalline samples. Specific heat 𝐶(𝑇 ) measurement reveals a bulk superconductivity with 𝑇c ≃ 3.75 K and a specific heat jump ratio of 1.42. All these results are in agreement with a moderately electron-phonon coupled, type-II Bardeen-Cooper-Schrieffer superconductor.

$^{181}$Ta Nuclear quadrupole resonance study of non-centrosymmetric superconductor PbTaSe$_2$

“…Figure 3 shows the temperature dependence of 1/T 1 for the Ta(1) site, which was measured from the NQR peaks corresponding to m = ±1/2 ↔ ±3/2 transition. The upper panel of this figure shows the T dependence of the AC susceptibility measured using an in situ NQR coil (circles), together with that of the DC susceptibility by MPMS (solid line), indicating that bulk superconductivity takes place below T c ∼ 3.8 K, which is consistent with the values in previous reports [15,19,20,[23][24][25][26][27][28][29][30]36]. At normal states (T > T c ), 1/T 1 is proportional to temperature, which is generally seen in non-correlated normal metals.…”

“…Many experimental studies have been carried out for detection of the unique superconducting state of PbTaSe 2 . However, so far only the signatures of conventional BCStype s-wave superconductivity have been reported, including heat capacity [23][24][25], thermal conductivity [26], tunnel diode oscillator [27], STM [28], and µSR [29]. Microscopic evidence for conventional BCS-type s-wave superconductivity was also reported by 207 Pb nuclear magnetic resonance (NMR) measurements [30], which were performed for vortex states in an external magnetic field µ 0 H = 0.19 T close to µ 0 H c c2 (T = 0) ≈ 0.3 T [23][24][25][26].…”

“…However, so far only the signatures of conventional BCStype s-wave superconductivity have been reported, including heat capacity [23][24][25], thermal conductivity [26], tunnel diode oscillator [27], STM [28], and µSR [29]. Microscopic evidence for conventional BCS-type s-wave superconductivity was also reported by 207 Pb nuclear magnetic resonance (NMR) measurements [30], which were performed for vortex states in an external magnetic field µ 0 H = 0.19 T close to µ 0 H c c2 (T = 0) ≈ 0.3 T [23][24][25][26]. To elucidate hidden electronic states and superconducting properties in zero magnetic field, it is also desirable to perform 181 Ta NQR, which allows local electronic states of TaSe 2 layer to be probed directly.…”

Evidence for nematic superconductivity of topological surface states in PbTaSe2

“…Single crystals of PbTaSe 2 were grown by the chemical vapor transport methods as described in Refs. [33,34]. The crystal orientations were determined by X-ray Laue diffraction.…”

Topological Surface Superconductivity Induced by Hydrostatic Pressure-Enhanced Antisymmetric Spin-Orbit Coupling in Non-Centrosymmetric Superconductor PbTaSe2

“…High quality single crystals of PbTaSe 2 were grown by chemical vapor transport by using iodine as a transport agent. The details of single crystal growth and physical property characterization were reported elsewhere [29,31,32]. The crystal structure and its noncentrosymmetric nature have been examined by scanning transmission electron microscopy (STEM) along the [001] zoneaxis direction with high resolution.…”